When creating a coupon (Admins > Billing > Coupons) or assigning one to a membership, you can define its duration:
Forever: The coupon remains active for the entire duration of the subscription.
Months: Specify a number of months for the coupon to be applied (e.g., a 3-month introductory rate). After this period, the regular membership fee will be charged.
Once: The coupon is applied only to the first billing cycle.
These duration options are only applicable to subscription-based memberships. For one-time purchases like punch cards or store items, these settings are not relevant. Applying a "Months" duration to a one-time purchase coupon will result in an error. For such items, using either "Forever" or "Once" will achieve the same single-application discount.
If you create a promo code for a coupon, you can set a separate expiration date for the promo code itself.