John Burnett
First, check to see whether your bank has made some sort of change to the UCC rules by making its stop payments non-expiring by agreement. It's within the bank's ability to do so, but it may be "overkill" in an attempt to protect its customers from payees who swoop in two days after the end of the normal expiration period to take advantage of the fact that most customers don't bother to renew or extend their stop payments.
You could ask your IT folks or service provider whether the system can generate a pre-expiration notice on stop payments (assuming the actual expiration date has been entered on your records).
Brian Crow
John's answer addresses stop payments on checks. Note that NACHA rules require that the bank honor ACH stop payment requests on consumer accounts indefinitely without the customer renewing the stop order every six months.