I started a final year student project for small demo RTS game. If I do it in Unity Free and later decide that I need elements from Unity Pro, will I be able to transfer without problems?
Should be able to! That’s what I did. (almost precisely what I did, actually, only with a brawler, not an RTS…) As long as you don’t then try to go back to the free version (you’ll lose functionality, plus other things might go wrong), it should work just fine. Although, once you get used to all the awesome stuff in Unity Pro, there’s not really any going back at all- I’m not sure how I’d live without my profiler, and full-screen effect shaders are pretty cool.
There’s nothing to transfer; there is only one Unity app. It’s not like the free license is a separate version or anything. The only thing the Pro license does is enable certain features to work.