Since we are discussing the fact that coupons expire, let's look into that in a little more depth. These days, almost all coupons have an expiration date. Back in the day some coupons used to say "DO NOT EXPIRE" but I have not seen any of those in recent years.
Most coupons that come in the Sunday paper expire in approximately 2-3 months. The glaring exception are the Proctor & Gamble coupons. We got a P&G insert this past Sunday (8/28) and they all expire in one month (9/30). We happen to live deep in P&G land here in Ohio, and in fact are friends with several Proctoids (people who work at P&G), but I am not a fan of how they issue coupons. I'll delve into that on another day.
Many store coupons are only valid for the specific week in which they are issued. Printable coupons vary with regard to expiration date.
Many coupons expire on the last day of a month. Since today is the 30th, it's a great time to take a quick trip through your coupon binder and identify which coupons are expiring and decide if they are worth using. Nothing is worse than realizing you let a great coupon expire, so go take a look through. I pull all the coupons expiring on the 31st and separate off the ones I plan to use. I keep the others on the side just in case, but it eliminates the need for me to go through the binder a second time if I do it all at once.