cou·​pon | \ ˈkü-ˌpän [ koo-pon, kyoo- ]

a small piece of paper or digital code that allows one to get a service or product at a lower price (or for free)
a ticket or form authorizing purchases of rationed commodities
a part of a printed advertisement to be cut off to use as an order blank or inquiry form or to obtain a discount on merchandise or services