It seems that your project is still using the trial version of Telerik UI .dll files. More information on the matter is available in Getting tired of seeing trial messages in your ASP.NET AJAX application?
blog post. You may also find useful Upgrade the Version of Your Telerik ASP.NET Controls in 6 Easy Steps
blog post that sheds more light on how to easily upgrade your project with Telerik UI in six easy steps.
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