diff --git a/CHANGELOG.md b/CHANGELOG.md
index da31509..1e359e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,46 @@ All notable changes to WooCommerce Tier and Package Prices will be documented in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.3.1] - 2026-01-27
+
+### Changed
+
+- **Switched to SecureLicenseClient**: Upgraded from basic `LicenseClient` to `SecureLicenseClient` with HMAC-SHA256 response signature verification for enhanced security against tampering and replay attacks
+
+- **Added Server Secret Configuration**: New "Server Secret" field in License settings for secure communication with the license server
+
+### Added
+
+- **Rate Limit Handling**: Added proper handling of `RateLimitExceededException` with user-friendly messages showing retry wait time
+- **Signature Verification Error Handling**: Added dedicated handling for `SignatureException` when response signatures fail verification
+- **URL Validation Error Handling**: Added handling for `InvalidArgumentException` from SSRF protection in the license client
+
+### Security
+
+- Response signatures are now verified using HMAC-SHA256 with license-specific derived keys (RFC 5869 HKDF)
+- The license client now validates server URLs to prevent SSRF attacks (blocks private IP ranges)
+- HTTP connections require HTTPS unless explicitly allowed for localhost testing
+
+### Technical Details
+
+**License Client Upgrade**:
+
+- Changed from `LicenseClient` to `SecureLicenseClient`
+- Added `serverSecret` parameter for signature verification
+- Library updated from `v0.1.0` to `dev-main` with new security features
+
+**New Exception Handling**:
+
+- `RateLimitExceededException` - shows retry time to user
+- `SignatureException` - indicates server secret mismatch
+- `InvalidArgumentException` - invalid/blocked URL detected
+
+**New Settings Field**:
+
+- `wc_tpp_license_server_secret` (password type) for the shared secret
+
+---
+
 ## [1.3.0] - 2026-01-25
 
 ### Breaking Changes
diff --git a/composer.json b/composer.json
index ea78249..9f10730 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "magdev/wc-tier-package-prices",
     "description": "WooCommerce plugin for tier pricing and package prices with Twig templates",
-    "version": "1.3.0",
+    "version": "1.3.1",
     "type": "wordpress-plugin",
     "license": "GPL-2.0-or-later",
     "authors": [
@@ -19,7 +19,7 @@
     "require": {
         "php": ">=8.3",
         "twig/twig": "^3.0",
-        "magdev/wc-licensed-product-client": "^0.1"
+        "magdev/wc-licensed-product-client": "dev-main"
     },
     "autoload": {
         "classmap": [
diff --git a/includes/class-wc-tpp-settings.php b/includes/class-wc-tpp-settings.php
index c962cf8..6783ab4 100755
--- a/includes/class-wc-tpp-settings.php
+++ b/includes/class-wc-tpp-settings.php
@@ -154,6 +154,16 @@ if (!class_exists('WC_TPP_Settings')) {
                     'desc_tip' => true,
                 ),
 
+                array(
+                    'title'    => __('Server Secret', 'wc-tier-package-prices'),
+                    'desc'     => __('The shared secret for secure communication with the license server.', 'wc-tier-package-prices'),
+                    'id'       => 'wc_tpp_license_server_secret',
+                    'type'     => 'password',
+                    'default'  => '',
+                    'css'      => 'min-width:400px;',
+                    'desc_tip' => true,
+                ),
+
                 array(
                     'title' => __('License Status', 'wc-tier-package-prices'),
                     'type'  => 'wc_tpp_license_status',
@@ -188,13 +198,14 @@ if (!class_exists('WC_TPP_Settings')) {
 
             $license_key = sanitize_text_field(wp_unslash($_POST['license_key'] ?? ''));
             $server_url = esc_url_raw(wp_unslash($_POST['server_url'] ?? ''));
+            $server_secret = sanitize_text_field(wp_unslash($_POST['server_secret'] ?? ''));
 
-            if (empty($license_key) || empty($server_url)) {
-                wp_send_json_error(array('message' => __('License key and server URL are required.', 'wc-tier-package-prices')));
+            if (empty($license_key) || empty($server_url) || empty($server_secret)) {
+                wp_send_json_error(array('message' => __('License key, server URL, and server secret are required.', 'wc-tier-package-prices')));
             }
 
             try {
-                $client = $this->get_license_client($server_url);
+                $client = $this->get_license_client($server_url, $server_secret);
                 $domain = $this->get_current_domain();
                 $result = $client->validate($license_key, $domain);
 
@@ -212,16 +223,37 @@ if (!class_exists('WC_TPP_Settings')) {
                     'status'  => $this->get_cached_license_status(),
                 ));
 
+            } catch (\Magdev\WcLicensedProductClient\Exception\RateLimitExceededException $e) {
+                wp_send_json_error(array(
+                    'message' => sprintf(
+                        /* translators: %d: Number of seconds to wait */
+                        __('Rate limit exceeded. Please try again in %d seconds.', 'wc-tier-package-prices'),
+                        $e->retryAfter ?? 60
+                    ),
+                    'code'       => 'rate_limit_exceeded',
+                    'retry_after' => $e->retryAfter,
+                ));
+            } catch (\Magdev\WcLicensedProductClient\Security\SignatureException $e) {
+                delete_transient('wc_tpp_license_status');
+                wp_send_json_error(array(
+                    'message' => __('Response signature verification failed. Please check your server secret.', 'wc-tier-package-prices'),
+                    'code'    => 'signature_error',
+                ));
             } catch (\Magdev\WcLicensedProductClient\Exception\LicenseException $e) {
                 delete_transient('wc_tpp_license_status');
                 wp_send_json_error(array(
                     'message' => $e->getMessage(),
                     'code'    => $e->errorCode ?? 'unknown',
                 ));
+            } catch (\InvalidArgumentException $e) {
+                wp_send_json_error(array(
+                    'message' => $e->getMessage(),
+                    'code'    => 'invalid_url',
+                ));
             } catch (\Exception $e) {
                 delete_transient('wc_tpp_license_status');
                 wp_send_json_error(array(
-                    'message' => $e->getMessage(),
+                    'message' => __('An unexpected error occurred. Please try again.', 'wc-tier-package-prices'),
                     'code'    => 'exception',
                 ));
             }
@@ -239,13 +271,14 @@ if (!class_exists('WC_TPP_Settings')) {
 
             $license_key = sanitize_text_field(wp_unslash($_POST['license_key'] ?? ''));
             $server_url = esc_url_raw(wp_unslash($_POST['server_url'] ?? ''));
+            $server_secret = sanitize_text_field(wp_unslash($_POST['server_secret'] ?? ''));
 
-            if (empty($license_key) || empty($server_url)) {
-                wp_send_json_error(array('message' => __('License key and server URL are required.', 'wc-tier-package-prices')));
+            if (empty($license_key) || empty($server_url) || empty($server_secret)) {
+                wp_send_json_error(array('message' => __('License key, server URL, and server secret are required.', 'wc-tier-package-prices')));
             }
 
             try {
-                $client = $this->get_license_client($server_url);
+                $client = $this->get_license_client($server_url, $server_secret);
                 $domain = $this->get_current_domain();
                 $result = $client->activate($license_key, $domain);
 
@@ -269,14 +302,34 @@ if (!class_exists('WC_TPP_Settings')) {
 
                 wp_send_json_error(array('message' => $result->message));
 
+            } catch (\Magdev\WcLicensedProductClient\Exception\RateLimitExceededException $e) {
+                wp_send_json_error(array(
+                    'message' => sprintf(
+                        /* translators: %d: Number of seconds to wait */
+                        __('Rate limit exceeded. Please try again in %d seconds.', 'wc-tier-package-prices'),
+                        $e->retryAfter ?? 60
+                    ),
+                    'code'       => 'rate_limit_exceeded',
+                    'retry_after' => $e->retryAfter,
+                ));
+            } catch (\Magdev\WcLicensedProductClient\Security\SignatureException $e) {
+                wp_send_json_error(array(
+                    'message' => __('Response signature verification failed. Please check your server secret.', 'wc-tier-package-prices'),
+                    'code'    => 'signature_error',
+                ));
             } catch (\Magdev\WcLicensedProductClient\Exception\LicenseException $e) {
                 wp_send_json_error(array(
                     'message' => $e->getMessage(),
                     'code'    => $e->errorCode ?? 'unknown',
                 ));
-            } catch (\Exception $e) {
+            } catch (\InvalidArgumentException $e) {
                 wp_send_json_error(array(
                     'message' => $e->getMessage(),
+                    'code'    => 'invalid_url',
+                ));
+            } catch (\Exception $e) {
+                wp_send_json_error(array(
+                    'message' => __('An unexpected error occurred. Please try again.', 'wc-tier-package-prices'),
                     'code'    => 'exception',
                 ));
             }
@@ -285,14 +338,18 @@ if (!class_exists('WC_TPP_Settings')) {
         /**
          * Get license client instance
          *
-         * @param string $server_url License server URL.
+         * Uses SecureLicenseClient for HMAC signature verification.
+         *
+         * @param string $server_url    License server URL.
+         * @param string $server_secret Shared secret for signature verification.
          * @return \Magdev\WcLicensedProductClient\LicenseClientInterface
          */
-        private function get_license_client(string $server_url): \Magdev\WcLicensedProductClient\LicenseClientInterface {
+        private function get_license_client(string $server_url, string $server_secret): \Magdev\WcLicensedProductClient\LicenseClientInterface {
             $httpClient = \Symfony\Component\HttpClient\HttpClient::create();
-            return new \Magdev\WcLicensedProductClient\LicenseClient(
+            return new \Magdev\WcLicensedProductClient\SecureLicenseClient(
                 httpClient: $httpClient,
                 baseUrl: $server_url,
+                serverSecret: $server_secret,
             );
         }
 
@@ -402,6 +459,7 @@ if (!class_exists('WC_TPP_Settings')) {
                     return {
                         license_key: $('#wc_tpp_license_key').val(),
                         server_url: $('#wc_tpp_license_server_url').val(),
+                        server_secret: $('#wc_tpp_license_server_secret').val(),
                         nonce: '<?php echo esc_js($nonce); ?>'
                     };
                 }
@@ -420,8 +478,8 @@ if (!class_exists('WC_TPP_Settings')) {
 
                 $validateBtn.on('click', function() {
                     var data = getLicenseData();
-                    if (!data.license_key || !data.server_url) {
-                        alert('<?php echo esc_js(__('Please enter both license server URL and license key.', 'wc-tier-package-prices')); ?>');
+                    if (!data.license_key || !data.server_url || !data.server_secret) {
+                        alert('<?php echo esc_js(__('Please enter license server URL, license key, and server secret.', 'wc-tier-package-prices')); ?>');
                         return;
                     }
 
@@ -443,8 +501,8 @@ if (!class_exists('WC_TPP_Settings')) {
 
                 $activateBtn.on('click', function() {
                     var data = getLicenseData();
-                    if (!data.license_key || !data.server_url) {
-                        alert('<?php echo esc_js(__('Please enter both license server URL and license key.', 'wc-tier-package-prices')); ?>');
+                    if (!data.license_key || !data.server_url || !data.server_secret) {
+                        alert('<?php echo esc_js(__('Please enter license server URL, license key, and server secret.', 'wc-tier-package-prices')); ?>');
                         return;
                     }
 
diff --git a/languages/wc-tier-package-prices-de_CH.mo b/languages/wc-tier-package-prices-de_CH.mo
index 977eefd..2897606 100644
Binary files a/languages/wc-tier-package-prices-de_CH.mo and b/languages/wc-tier-package-prices-de_CH.mo differ
diff --git a/languages/wc-tier-package-prices-de_CH.po b/languages/wc-tier-package-prices-de_CH.po
index 4a0b7b5..a61bc70 100644
--- a/languages/wc-tier-package-prices-de_CH.po
+++ b/languages/wc-tier-package-prices-de_CH.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Zugriff verweigert."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "Lizenzschlüssel und Server-URL sind erforderlich."
+msgid "Server Secret"
+msgstr "Server-Geheimnis"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Bitte geben Sie sowohl die Lizenzserver-URL als auch den Lizenzschlüssel ein."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Das gemeinsame Geheimnis für die sichere Kommunikation mit dem Lizenzserver."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "Lizenzschlüssel, Server-URL und Server-Geheimnis sind erforderlich."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Anfragelimit überschritten. Bitte versuchen Sie es in %d Sekunden erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Überprüfung der Antwortsignatur fehlgeschlagen. Bitte überprüfen Sie Ihr Server-Geheimnis."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Ein unerwarteter Fehler ist aufgetreten. Bitte versuchen Sie es erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Bitte geben Sie die Lizenzserver-URL, den Lizenzschlüssel und das Server-Geheimnis ein."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-de_CH_informal.mo b/languages/wc-tier-package-prices-de_CH_informal.mo
index aa35d06..64b6c14 100644
Binary files a/languages/wc-tier-package-prices-de_CH_informal.mo and b/languages/wc-tier-package-prices-de_CH_informal.mo differ
diff --git a/languages/wc-tier-package-prices-de_CH_informal.po b/languages/wc-tier-package-prices-de_CH_informal.po
index 4e0ae60..82a4f29 100644
--- a/languages/wc-tier-package-prices-de_CH_informal.po
+++ b/languages/wc-tier-package-prices-de_CH_informal.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Zugriff verweigert."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "Lizenzschlüssel und Server-URL sind erforderlich."
+msgid "Server Secret"
+msgstr "Server-Geheimnis"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Bitte gib sowohl die Lizenzserver-URL als auch den Lizenzschlüssel ein."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Das gemeinsame Geheimnis für die sichere Kommunikation mit dem Lizenzserver."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "Lizenzschlüssel, Server-URL und Server-Geheimnis sind erforderlich."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Anfragelimit überschritten. Bitte versuche es in %d Sekunden erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Überprüfung der Antwortsignatur fehlgeschlagen. Bitte überprüfe dein Server-Geheimnis."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Ein unerwarteter Fehler ist aufgetreten. Bitte versuche es erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Bitte gib die Lizenzserver-URL, den Lizenzschlüssel und das Server-Geheimnis ein."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-de_DE.mo b/languages/wc-tier-package-prices-de_DE.mo
index 074655f..39a2868 100644
Binary files a/languages/wc-tier-package-prices-de_DE.mo and b/languages/wc-tier-package-prices-de_DE.mo differ
diff --git a/languages/wc-tier-package-prices-de_DE.po b/languages/wc-tier-package-prices-de_DE.po
index 2f1d9ce..ee2d551 100644
--- a/languages/wc-tier-package-prices-de_DE.po
+++ b/languages/wc-tier-package-prices-de_DE.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Zugriff verweigert."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "Lizenzschlüssel und Server-URL sind erforderlich."
+msgid "Server Secret"
+msgstr "Server-Geheimnis"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Bitte geben Sie sowohl die Lizenzserver-URL als auch den Lizenzschlüssel ein."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Das gemeinsame Geheimnis für die sichere Kommunikation mit dem Lizenzserver."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "Lizenzschlüssel, Server-URL und Server-Geheimnis sind erforderlich."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Anfragelimit überschritten. Bitte versuchen Sie es in %d Sekunden erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Überprüfung der Antwortsignatur fehlgeschlagen. Bitte überprüfen Sie Ihr Server-Geheimnis."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Ein unerwarteter Fehler ist aufgetreten. Bitte versuchen Sie es erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Bitte geben Sie die Lizenzserver-URL, den Lizenzschlüssel und das Server-Geheimnis ein."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-de_DE_informal.mo b/languages/wc-tier-package-prices-de_DE_informal.mo
index fd641fb..b338813 100644
Binary files a/languages/wc-tier-package-prices-de_DE_informal.mo and b/languages/wc-tier-package-prices-de_DE_informal.mo differ
diff --git a/languages/wc-tier-package-prices-de_DE_informal.po b/languages/wc-tier-package-prices-de_DE_informal.po
index a446d13..5b46e58 100644
--- a/languages/wc-tier-package-prices-de_DE_informal.po
+++ b/languages/wc-tier-package-prices-de_DE_informal.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Zugriff verweigert."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "Lizenzschlüssel und Server-URL sind erforderlich."
+msgid "Server Secret"
+msgstr "Server-Geheimnis"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Bitte gib sowohl die Lizenzserver-URL als auch den Lizenzschlüssel ein."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Das gemeinsame Geheimnis für die sichere Kommunikation mit dem Lizenzserver."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "Lizenzschlüssel, Server-URL und Server-Geheimnis sind erforderlich."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Anfragelimit überschritten. Bitte versuche es in %d Sekunden erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Überprüfung der Antwortsignatur fehlgeschlagen. Bitte überprüfe dein Server-Geheimnis."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Ein unerwarteter Fehler ist aufgetreten. Bitte versuche es erneut."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Bitte gib die Lizenzserver-URL, den Lizenzschlüssel und das Server-Geheimnis ein."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-en_US.mo b/languages/wc-tier-package-prices-en_US.mo
index f75db7c..4628058 100644
Binary files a/languages/wc-tier-package-prices-en_US.mo and b/languages/wc-tier-package-prices-en_US.mo differ
diff --git a/languages/wc-tier-package-prices-en_US.po b/languages/wc-tier-package-prices-en_US.po
index 8987ea3..1ff2228 100644
--- a/languages/wc-tier-package-prices-en_US.po
+++ b/languages/wc-tier-package-prices-en_US.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Permission denied."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "License key and server URL are required."
+msgid "Server Secret"
+msgstr "Server Secret"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Please enter both license server URL and license key."
+msgid "The shared secret for secure communication with the license server."
+msgstr "The shared secret for secure communication with the license server."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "License key, server URL, and server secret are required."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Rate limit exceeded. Please try again in %d seconds."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Response signature verification failed. Please check your server secret."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "An unexpected error occurred. Please try again."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Please enter license server URL, license key, and server secret."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-fr_CH.mo b/languages/wc-tier-package-prices-fr_CH.mo
index 039b8a3..b058265 100644
Binary files a/languages/wc-tier-package-prices-fr_CH.mo and b/languages/wc-tier-package-prices-fr_CH.mo differ
diff --git a/languages/wc-tier-package-prices-fr_CH.po b/languages/wc-tier-package-prices-fr_CH.po
index 8b4b308..42dd529 100644
--- a/languages/wc-tier-package-prices-fr_CH.po
+++ b/languages/wc-tier-package-prices-fr_CH.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Accès refusé."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "La clé de licence et l'URL du serveur sont requises."
+msgid "Server Secret"
+msgstr "Secret serveur"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Veuillez entrer l'URL du serveur de licence et la clé de licence."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Le secret partagé pour la communication sécurisée avec le serveur de licence."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "La clé de licence, l'URL du serveur et le secret serveur sont requis."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Limite de requêtes dépassée. Veuillez réessayer dans %d secondes."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "La vérification de la signature a échoué. Veuillez vérifier votre secret serveur."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Une erreur inattendue s'est produite. Veuillez réessayer."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Veuillez entrer l'URL du serveur de licence, la clé de licence et le secret serveur."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices-it_CH.mo b/languages/wc-tier-package-prices-it_CH.mo
index 45b2b6f..d9981a8 100644
Binary files a/languages/wc-tier-package-prices-it_CH.mo and b/languages/wc-tier-package-prices-it_CH.mo differ
diff --git a/languages/wc-tier-package-prices-it_CH.po b/languages/wc-tier-package-prices-it_CH.po
index 37b3b71..a9d9d83 100644
--- a/languages/wc-tier-package-prices-it_CH.po
+++ b/languages/wc-tier-package-prices-it_CH.po
@@ -359,12 +359,33 @@ msgid "Permission denied."
 msgstr "Accesso negato."
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
-msgstr "La chiave di licenza e l'URL del server sono obbligatori."
+msgid "Server Secret"
+msgstr "Segreto del server"
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
-msgstr "Inserisci sia l'URL del server di licenza che la chiave di licenza."
+msgid "The shared secret for secure communication with the license server."
+msgstr "Il segreto condiviso per la comunicazione sicura con il server di licenza."
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr "La chiave di licenza, l'URL del server e il segreto del server sono obbligatori."
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr "Limite di richieste superato. Per favore riprova tra %d secondi."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr "Verifica della firma della risposta fallita. Per favore controlla il tuo segreto del server."
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr "Si è verificato un errore imprevisto. Per favore riprova."
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
+msgstr "Inserisci l'URL del server di licenza, la chiave di licenza e il segreto del server."
 
 #: includes/class-wc-tpp-settings.php
 msgid "Validation failed."
diff --git a/languages/wc-tier-package-prices.pot b/languages/wc-tier-package-prices.pot
index e095067..7896ff5 100644
--- a/languages/wc-tier-package-prices.pot
+++ b/languages/wc-tier-package-prices.pot
@@ -2,9 +2,9 @@
 # This file is distributed under the GPL v2 or later.
 msgid ""
 msgstr ""
-"Project-Id-Version: WooCommerce Tier and Package Prices 1.2.7\n"
+"Project-Id-Version: WooCommerce Tier and Package Prices 1.3.1\n"
 "Report-Msgid-Bugs-To: https://src.bundespruefstelle.ch/wc-tier-package-prices\n"
-"POT-Creation-Date: 2025-12-30 00:00+0000\n"
+"POT-Creation-Date: 2026-01-27 00:00+0000\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
@@ -332,11 +332,32 @@ msgid "Permission denied."
 msgstr ""
 
 #: includes/class-wc-tpp-settings.php
-msgid "License key and server URL are required."
+msgid "Server Secret"
 msgstr ""
 
 #: includes/class-wc-tpp-settings.php
-msgid "Please enter both license server URL and license key."
+msgid "The shared secret for secure communication with the license server."
+msgstr ""
+
+#: includes/class-wc-tpp-settings.php
+msgid "License key, server URL, and server secret are required."
+msgstr ""
+
+#: includes/class-wc-tpp-settings.php
+#. translators: %d: Number of seconds to wait
+msgid "Rate limit exceeded. Please try again in %d seconds."
+msgstr ""
+
+#: includes/class-wc-tpp-settings.php
+msgid "Response signature verification failed. Please check your server secret."
+msgstr ""
+
+#: includes/class-wc-tpp-settings.php
+msgid "An unexpected error occurred. Please try again."
+msgstr ""
+
+#: includes/class-wc-tpp-settings.php
+msgid "Please enter license server URL, license key, and server secret."
 msgstr ""
 
 #: includes/class-wc-tpp-settings.php
diff --git a/wc-tier-and-package-prices.php b/wc-tier-and-package-prices.php
index 0e54e80..72e275e 100755
--- a/wc-tier-and-package-prices.php
+++ b/wc-tier-and-package-prices.php
@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.3.0
+ * Version: 1.3.1
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -46,7 +46,7 @@ if (!function_exists('wc_tpp_php_version_notice')) {
 
 // Define plugin constants
 if (!defined('WC_TPP_VERSION')) {
-    define('WC_TPP_VERSION', '1.3.0');
+    define('WC_TPP_VERSION', '1.3.1');
 }
 if (!defined('WC_TPP_PLUGIN_DIR')) {
     define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));