Yes. PayCoupons stores all closed purchase and sales contracts in its database. This applies both to contracts between a user and PayCoupons as a platform provider, and to the contracts between users about the purchase and sale of coupons, as facilitated by the PayCoupons platform.
Note that contracts between users are prepared by making offers and orders, but finalized (made irrevocable) only by so-called coupon exchanges that happen automatically on the PayCoupons platform.
You can get an overview of the exchanges you have become part of by looking for "Coupons exchanged" entries under the "Activity" menu item when you are logged in on the PayCoupons platform. You also receive a confirmation e-mail whenever a new exchange is made.