In my game I have a developer product and I want it to be where when someone buys the developer product, something happens in the server that they're in. I cannot find anything about this type of thing anywhere. Could someone help me?
There's a function that is a part of MarketplaceService called MarketplaceService.ProcessReceipt.
One thing that I also recommend is using a MarketplaceService module, which will allow you to make the system without as many lines of code in a script.
I normally use this one, but I bet there's others out there.