Is there a way I can give them access to the paid version of the game? So theres no need to buy it for them.
You buy access to a project's files, not access to individual files.
The faq details the different options you have. If you change the pricing, this should be considered. You can think of paying someone 2 $ for a free game that would be later set to a minimut of 10 $ to have bought the game at a discount.