Sorry for the late reply. Our legal department is very busy these days. The answer to your question is, no, you don't have to get any kind of contracts with AMD in order to legally sell our parts in your own device. As long as you are buying the parts from a distributor or a retail vendor, you have no need to enter into a contract with AMD.
There are no royalties on using our parts in a computer system that you build.
Hope that answers your question. If you think I am misunderstanding the question, then please let me know and provide more information.