I’ve been using Amazon’s Subscribe-and-Save program for several months, and it’s pretty neat. Basically, you tell them how often you want to receive a certain product, e.g. snack crackers, and they ship them automatically based on that interval. You also get a discount on each order, typically around 15%. And so you don’t feel locked in, Amazon sends you an email before each shipment and gives you the opportunity to cancel it, just in case you don’t need more of the item yet. Overall, the service saves me time and is a nice way for Amazon to encourage repeat purchases.

But there’s one scenario where Subscribe-and-Save breaks down. If Amazon stops carrying the product you subscribed to, it stays in your subscriptions page without any way to search for a replacement item or to request that they carry it again. In fact, I don’t even think they send you an email about the missing product until the next scheduled ship date comes along. By that point, you’re already expecting the order to be sent, and you haven’t had the chance to make alternate plans and choose something else.

Granted, this is only a minor annoyance. The service is still quite valuable even if discontinued products can throw Amazon’s system for a loop. But the takeaway is clear: if you’re giving customers a way to save time by automating their recurring orders, it pays to make sure there are no glitches in that system. Products will be discontinued or replaced with similar items that carry different SKUs. Credit cards will expire and customers will forget to enter the new info. By planning for these inevitable issues, and letting customers know about them as far in advance as possible, you help people achieve their goal of a hassle-free buying process — while keeping your own recurring revenue streams intact.