Reuse dll telerik.mvc.dll

I would like know about telerik.mvc.dll included in the project. I have to pay? Case not, can I use in another project ?

Nopcommerce uses the Telerik controls. The answer to your question depends greatly under what license your derivative work will be released.  The thread https://www.nopcommerce.com/boards/t/22822/telerik-licensing-question.aspx explains in more detail.