From 3f9da3e2d7c7d946ed87441f07c581ef0cbb8a61 Mon Sep 17 00:00:00 2001 From: Dinko Krastev Date: Tue, 21 Oct 2025 17:20:43 +0300 Subject: [PATCH 1/3] KB: Validate License Key in Add-in --- .../add-license-key-in-add-in-project.md | 44 +++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 knowledge-base/add-license-key-in-add-in-project.md diff --git a/knowledge-base/add-license-key-in-add-in-project.md b/knowledge-base/add-license-key-in-add-in-project.md new file mode 100644 index 000000000..faafa3aa1 --- /dev/null +++ b/knowledge-base/add-license-key-in-add-in-project.md @@ -0,0 +1,44 @@ +--- +title: Telerik License Watermark Appears When UI for WinForms Form is Used in Add-In Project +description: The invalid or missing Telerik license key warning is displayed in an Add-In project, like Excel/Word VST, and others. +page_title: Telerik License Key Invalid or Missing Message Box and Watermark Displayed in a Add-in/Plugin Project +type: troubleshooting +slug: add-license-key-in-add-in-project +position: 0 +tags: licensing,installation, telerik, licensing, license, key, not, found, addin +res_type: kb +--- + +## Environment + +|Product Version|Product|Author| +|----|----|----| +|2025.3.812|Telerik UI for WinForms|[Dinko Krastev](https://www.telerik.com/blogs/author/dinko-krastev)| + +## Description + +The invalid/missing Telerik license key dialog is shown in addin (like Excel VSTO Add-in) projects even when a valid license is installed. + +## Solution + +This happens because there is no proper main window and application context, which means that the licensing mechanism cannot be evaluated as expected. To resolve this, use the `TelerikLicensing.Register` static method. + +Here is a possible solution to resolve the licensing mechanism and remove the Watermark if the license key is valid: + +* Ensure that each project, library in your Add-in/Plugin Project is referencing the Telerik.Licensing NuGet. The NuGet is located on the [NuGet.org server](https://www.nuget.org/). + +* Ensure that the Watermark does not appear in your Add-In/Plugin when run as standalone application in Visual Studio. + +* Call the TelerikLicensing.Register() method arly as possible, before initializing any Telerik controls. Keep in mind that RadForm is also a control from our suite. You will need to consider placing it as early as possible in your plug-in’s loading process. + +````C# + +public class TelerikHelper +{ + public static void Register() => Telerik.Licensing.TelerikLicensing.Register(); +} + +```` + + + From 1d2caaf31a8d24a7d3d69fc912fcfec42aa1ce11 Mon Sep 17 00:00:00 2001 From: Nadya Todorova <48494959+nade7o@users.noreply.github.com> Date: Fri, 31 Oct 2025 11:27:02 +0200 Subject: [PATCH 2/3] Update add-license-key-in-add-in-project.md --- knowledge-base/add-license-key-in-add-in-project.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/knowledge-base/add-license-key-in-add-in-project.md b/knowledge-base/add-license-key-in-add-in-project.md index faafa3aa1..f5db4b0be 100644 --- a/knowledge-base/add-license-key-in-add-in-project.md +++ b/knowledge-base/add-license-key-in-add-in-project.md @@ -5,7 +5,7 @@ page_title: Telerik License Key Invalid or Missing Message Box and Watermark Dis type: troubleshooting slug: add-license-key-in-add-in-project position: 0 -tags: licensing,installation, telerik, licensing, license, key, not, found, addin +tags: licensing, installation, telerik, licensing, license, key, not, found, addin res_type: kb --- @@ -25,11 +25,11 @@ This happens because there is no proper main window and application context, whi Here is a possible solution to resolve the licensing mechanism and remove the Watermark if the license key is valid: -* Ensure that each project, library in your Add-in/Plugin Project is referencing the Telerik.Licensing NuGet. The NuGet is located on the [NuGet.org server](https://www.nuget.org/). +* Ensure that each project library in your Add-in/Plugin Project is referencing the Telerik.Licensing NuGet. The Licensing NuGet is located on the [NuGet.org server](https://www.nuget.org/). -* Ensure that the Watermark does not appear in your Add-In/Plugin when run as standalone application in Visual Studio. +* Ensure that the Watermark does not appear in your Add-In/Plugin when run as a standalone application in Visual Studio. -* Call the TelerikLicensing.Register() method arly as possible, before initializing any Telerik controls. Keep in mind that RadForm is also a control from our suite. You will need to consider placing it as early as possible in your plug-in’s loading process. +* Call the TelerikLicensing.Register() method as early as possible, before initializing any Telerik controls. Keep in mind that RadForm is also a control from our suite. You will need to consider placing it as early as possible in your plug-in’s loading process. ````C# From 41e00c572cd07bb89617bfb30f25f1f644190f4d Mon Sep 17 00:00:00 2001 From: Nadya Todorova <48494959+nade7o@users.noreply.github.com> Date: Fri, 31 Oct 2025 11:27:33 +0200 Subject: [PATCH 3/3] Update add-license-key-in-add-in-project.md --- knowledge-base/add-license-key-in-add-in-project.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/knowledge-base/add-license-key-in-add-in-project.md b/knowledge-base/add-license-key-in-add-in-project.md index f5db4b0be..60fce7d0d 100644 --- a/knowledge-base/add-license-key-in-add-in-project.md +++ b/knowledge-base/add-license-key-in-add-in-project.md @@ -27,7 +27,7 @@ Here is a possible solution to resolve the licensing mechanism and remove the Wa * Ensure that each project library in your Add-in/Plugin Project is referencing the Telerik.Licensing NuGet. The Licensing NuGet is located on the [NuGet.org server](https://www.nuget.org/). -* Ensure that the Watermark does not appear in your Add-In/Plugin when run as a standalone application in Visual Studio. +* Ensure that the watermark does not appear in your Add-In/Plugin when run as a standalone application in Visual Studio. * Call the TelerikLicensing.Register() method as early as possible, before initializing any Telerik controls. Keep in mind that RadForm is also a control from our suite. You will need to consider placing it as early as possible in your plug-in’s loading process.