I am building a dnn site where I want to use telerik controls.
Now the telerik.dll is included in DotNetNuke.
My question is can I reference this dll and use it in my modules for free?
(I am building commercial site)
I believe you are allowed to use it for free in the modules inside your site, as long as you are using the DNN wrappers for the telerik controls.
You can't sell your custom modules though.
This is my interpretation of the 'Are there special requirements under which DNN Modules are developed using Telerik controls?' section of the link posted by Ravi