I am making a GUI when you buy it you get the tool. But how do I use it?
PromptGamePassPurchaseFinished
is event, so use it like you would use any other event. Just read the documentation for the parameters provided when the event fires. https://www.robloxdev.com/api-reference/event/MarketplaceService/PromptGamePassPurchaseFinished
Edit: Fixed link.