Maybe I'm missing something but how does the system handle the growing list of payments that are stuck in limbo (i.e. memory) until the customer completes the p

Maybe I'm missing something but how does the system handle the growing list of payments that are stuck in limbo (i.e. memory) until the customer completes the payment (equivalent to abandoned carts)? Doesn't there need to be a mechanism for purging stale payment requests, lest memory eventually become completely consumed?