I want to make it that when you click a gui button, the gui that asks you to buy a gamepass pops up. If you buy it, you it prints something. But the thing is, I want it so you can buy it over and over, not just once. How do I do this?
What you're looking for is a Developer Product. You can create those under your game's config on the roblox site. Developer products can be purchased unlimited amount of times, as opposed to gamepasses which you own after purchasing.
Read more here: https://developer.roblox.com/articles/Developer-Products-In-Game-Purchases