A server and the like that can provide an opportunity for a user to confirm purchase of a reserved product, which sends a first message including an object for canceling reservation of a reserved product to a user via a message service, enabled to discriminate whether a message has been read, when the product arrives, cancels the reservation when the object is operated in a predetermined time after the first message is marked as read, determines whether the product is in stock when the object remains unoperated for the predetermined time after the first message is marked as read, finalizes purchase of the product when it is determined that the product is in stock, and sends a second message notifying that the product has been sold out to the user when it is determined that the product is out of stock.