When payment is made, it either succeeds or fails for whatever reason. In this case, though not important, the payment is made on a third party payment website, like Paypal, and a callback url is supplied for success or failure.
My question is should that success or error page expire, that is start returning a 404 after a set time or even immediately after it has been accessed once. There might be no security implications for allowing a notifications page live on forever, so this is more of a best practice question. But if there're security implications, I'll be glad to hear them.