I've used it before but I forgot how to do it, and I've checked the wiki (http://wiki.roblox.com/index.php?title=API:Class/MarketplaceService) and found nothing that's useful for it, any help appreciated.
local passId = 0000000 -- change this to your game pass ID. function isAuthenticated(player) -- checks to see if the player owns your pass return game:GetService("MarketplaceService"):PlayerOwnsAsset(player, passId) end game.Players.PlayerAdded:connect(function(plr) if isAuthenticated(plr) then print(plr.Name .. " has bought the game pass with id " .. passId) end end)