Read original post by Valentin Stoychev at The Telerik Blogs
As part of the Telerik “Q1.2012 Beta” package for Windows Phone we are releasing a new set of "Application Building Blocks" components. You can find more info on the idea of Application Building Blocks here.
Overview
Part of the application building blocks are the RadTrialApplicationReminder and RadTrialFeatureReminder components. With these 2 components developers can implement and adjust the trial functionality of their applications. You can implement application-wide trial notifications, or feature-specific trial notifications, with a lot of configurable options. Both components support time-based and usage-based trial restrictions.