So, I recently bought the public demo version of a game just to try it out, and now I want the full version. Is there a way to upgrade from demo to full version without having to just rebuy the game?
Not exactly sure what you mean by "bought public demo version". There's no demo version of MewnBase, and definitely not one for sale by me, what site did you buy it from?
If you bought the itch.io version, you do get all the updates for it for free as they're rrelease, as well as a free Steam key.
Cheers, and happy holidays.