If you have a Subway coupon, be it for a sandwich or cookies, beware that management will not accept them. My recent visit, I had a "cookie" coupon, clearly from Subway, without an expiration date or specified store, (received from local charity) and manager would not accept it.
Sure, it's just a 'cookie', but the whole point of a coupon is to bring customers in not 'bait and switch', as was the case.
By the way, on the receipt it had a 'take a Subway survey and receive free cookie". We'll see if they accept the validation coupon code.