I already bought the game from GamersGate, downloaded it and activated it (obviously) I just want to know if the save I'm using is going to work after the launch version is released.
They're very unlikely to work with the final release version, but there's nothing stopping you from continuing your save in the current build if you either hold off on the upgrade or create a different install for it.
You can do that if you enable edit mode. It pops up a face key when you press something (ctrl + E? something like that), which you can then paste in a file and boot up the game with the new face code afaik.