Added new kb article license-not-recognized-telerik-document-processing-libraries

distribution-and-licensing/license-key/setting-up-license-key.md

@@ -38,6 +38,9 @@ To activating the Document Processing Libraries:
 ```xml
 <PackageReference Include="Telerik.Licensing" Version="1.*" />
 ```
+
+>important The **Telerik.Licensing** verifies the DevSeat association at the time your classlib is built, and also provisions at runtime licenses in the Root app. When you have a setup such as **"Root app -> classlib -> Telerik UI"**, the Telerik UI will execute and verify the licensing for the classlib, but will not be applied transitively in the Root app. That's why you **need to add the Telerik.Licensing NuGet package reference to Root app manually**.
+
 When you build the project, the _Telerik.Licensing_ NuGet package automatically locates the license file and uses it to activate the product.
 
 >important If your project doesn’t use NuGet packages, see [Adding a License Key to Projects without NuGet References](#adding-a-license-key-to-projects-without-nuget-references).
@@ -70,4 +73,5 @@ Whenever you purchase a new license or renew an existing one, always [download a
 * [Handling License Key File Name and Environment Variable Name Changes in the 2025 Q1 Release]({%slug handling-license-file-name-changes%})
 * [Telerik.Licensing NuGet package is not available on the Telerik NuGet feed]({%slug dpl-telerik-licensing-nuget-feed%})
 * [Diagnostic Options for Telerik Licensing]({%slug telerik-trial-version-message-diagnostic-options%})
+* [Resolving License Validation Issues in Telerik Document Processing Libraries]({%slug license-not-recognized-telerik-document-processing-libraries%})
 

knowledge-base/license-not-recognized-telerik-document-processing-libraries.md

@@ -0,0 +1,56 @@
+---
+title: Resolving License Validation Issues in Telerik Document Processing Libraries
+description: Troubleshooting the issue where the license is not recognized during runtime in Telerik Document Processing Libraries.
+type: troubleshooting
+page_title: License Not Recognized in Telerik Document Processing Libraries
+meta_title: License Not Recognized in Telerik Document Processing Libraries
+slug: license-not-recognized-telerik-document-processing-libraries
+tags: telerik, document, processing, license, validation, runtime, issues, licensing, diagnostics
+res_type: kb
+ticketid: 1690929
+---
+
+## Environment
+
+| Version | Product | Author | 
+| ---- | ---- | ---- | 
+| 2025.2.520| RadPdfProcessing |[Desislava Yordanova](https://www.telerik.com/blogs/author/desislava-yordanova)| 
+
+## Description
+
+This article aims to address potential licensing issues while generating Excel (or PDF, DOCX, etc.) files with Telerik Document Processing Libraries during **runtime** testing. The generated file contains a "License" sheet (or a watermark) with a trial message, despite the **Build Output** window indicating a valid license. The issue arises in a multi-project (e.g. Blazor WASM) application setup, where dependencies are shared across projects.
+
+## Cause
+
+This issue generally occurs due to incomplete license validation during runtime in complex setups, particularly when using shared libraries or plugin architectures. *Even if the license is validated during build time, runtime environments may fail to recognize it due to transitive dependency limitations.*
+
+## Solution
+
+The **Telerik.Licensing** verifies the DevSeat association at the time your classlib is built, and also provisions at runtime licenses in the Root app. When you have a setup such as **"Root app -> classlib -> Telerik UI"**, the Telerik UI will execute and verify the licensing for the classlib, but will not be applied transitively in the Root app. That's why you **need to add the Telerik.Licensing NuGet package reference to Root app manually**.
+
+To ensure proper license validation and eliminate trial messages, follow the steps below:
+
+* **Direct Package References**: Add references to the **Telerik.Licensing** package directly in the Root project. This resolves transitive dependency limitations.
+
+* **Explicit License Registration**: Add a call to `TelerikLicensing.Register()` early in your application lifecycle. For Blazor WASM applications, include this call in the `Program.cs` file. This approach validates the license explicitly.
+
+* **Verify Assemblies**: Ensure **no trial** versions of Telerik assemblies are referenced in any project. Replace [trial assemblies]({%slug upgrade-trial-to-licensed-version%}) with licensed ones, if such even exist.
+
+* **Enable Diagnostics**: Add the following property to your `.csproj` file to enable detailed licensing diagnostics during build and runtime:
+   ```xml
+   <PropertyGroup>
+       <TelerikLicensingVerbosity>diagnostic</TelerikLicensingVerbosity>
+   </PropertyGroup>
+   ```
+   Review the diagnostic output for clues about license validation issues.
+
+* **Avoid Environment Variables**: Use only the `telerik-license.txt` file for license delivery instead of environment variables, which can cause issues due to length limitations.
+
+By following these steps, runtime validation issues should resolve, and the trial message will no longer appear in generated documents.
+
+## See Also
+
+- [Telerik Document Processing Licensing Overview]({%slug introduction%})
+- [Setting Up Your Telerik Document Processing Libraries License Key]({%slug setting-up-license-key%})
+- [Using TelerikLicensing.Register Method]({%slug adding-license-key-ci-cd-services%}#using-teleriklicensingregister-method-on-aws-lambdas)
+- [Diagnostic Options for Telerik Licensing]({%slug telerik-trial-version-message-diagnostic-options%})