When Do Coupons with a Set Duration Expire?

Coupons created with a specific duration will expire 1 hour prior to the original hour they were created at.

For example, if a customer redeems a coupon with a 1-month duration, the coupon will effectively expire in 29 days and 23 hours from the time of redemption. This is because the expiration calculation subtracts one hour from the exact moment of its creation/redemption after the full duration has passed.