Developer licenses come with modified DLLs, which work without displaying copyright messages. If you have a Developer license for one or more of the Telerik components, you only need to ensure that you are using the developer build when downloading the control(s). These builds have the Dev abbreviation in their file names.
If your application is displaying a copyright message intermittently, this means that you are using a trial version of the product. Log in to your Telerik account and download the developer build through the Products & Subscriptions menu and its Purchased Products section. To update your project, please take a look at the Upgrading the Trial License to a Production License section for step-by-step instructions.
The free trial licenses of all Telerik products are fully functional and will work for an unlimited time but with copyright message (see below) displayed randomly on the page.
The trial licenses will occasionally display the following message on your webform:
Thank you for using the Trial Version of Telerik® UI for ASP.NET AJAX to build more powerful applications faster. Purchase the Commercial Version now to get access to all product updates and the Telerik expert support.