You should remove the parenthesis at
Marketplaceservice.ProcessReceipt = processReceipt()
instead it should be
Marketplaceservice.ProcessReceipt = processReceipt
also you should check if the receipt product Id is equal to productId before giving them the bonus.
also change
local product ID = 1232493084
to
local productID = 1232493084
because that will cause an error.