The new Telerik licensing depends on putting a reference to the license key into the 'base' application. The assumption is that you have control over all the code.
Dynamics GP developers don't, 'Dynamics.exe' is out of our control. I've been working with Telerik support for a bit (who doesn't love unlimited free support?) and below are the exact steps to get it working. I'll also include any other reading that I have, in case my solution does not work for you.