Why? you can keep track how many times the bought it using a datastore.
The only other way is to make people delete their gamepass from their inventory so they can buy it again
You can’t, if you really want it on the website, you have to tell players to remove the gamepass from their inventory or have multiple of the same gamepasses so that they can buy 3 or more but that seems like more of a hassle than just using developer products.
Thinking better about it, your approach might be good since for this case I’m using it for in-game currency, gamepasses would make more sense if it was like a VIP or a Item