DT3 Pro -> DT4 Server upgrade path?

Is there any way to upgrade from a DT3 Pro license to DT4 Server?

Also, is there any chance you would consider a slight discount on the purchase price (not renewal) if you restrict the number of users on the server to 1? I myself will be the only user of the server. The whole purpose for me is to gain access on my windows machine, and not to share with others in an enterprise setting.

Thanks!