Me: Not sure if I can use both of these. These [printed coupon for rewards] are from this past year, so I assume that is fine. But these other ones are from 2 years ago. Costco: Why would they expire? Me: … Why indeed. OK.

(Many businesses will eventually want their unredeemed liabilities to expire. It’s a much more definitive way of doing the accounting, and also allows them to recognize so-called breakage revenue.)