The pop up "Before we start..." you would get after entering the registration code for the standard license looks pretty much the same as before you entered but the wording is different. It addresses the standard/premium situation of the particular scene that is currently loaded instead of the free/standard situation.
In Help->About this Territory you can see in the title bar which version of the territory is currently loaded.
Currently it is a 2-step process until you get to the full version of a particular territory: the first to upgrade from free to standard, and then from standard to premium. Any additional territory's upgrade to premium would be an additional step (the standard license is valid for all territories).
We are aware, that it is a little bit confusing, and we're working on ideas to simplify this and make it better understandable.