Hello Satish Chadha,
Thanks for contacting us.
You need only one license in this scenario because only one developer is going to use the controls in design time or the code-behind. The other developers may run an application with our assembly, however, they may not alter code, such as a property of the RadGrid, without having a license. Your other developers won't need to install any files. So, they can just have the application on their computer and not alter any of our code.
I hope that I have clarified our license agreement. Let me know if you have any questions.
the Telerik team