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Downloading and installing the purchased version of Telerik RadControls for Windows Phone 7 will only install that version to your machine. However your project will not be affected. That means that if the project was created with the trial version of the controls, the references will still point to the trial assemblies. To remove the trial message you should upgrade your project to the purchased version. This could be done easily using the Upgrade Wizard under the Telerik menu in Visual Studio. Here is a link to the documentation for reference: Windows Phone 7 Upgrade Wizard
Let me know if that helps.
the Telerik team
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