There is a feature in subway surfers that enables users to redeem codes in order to win rewards like new characters, keys, and other items without having to play the game for a significant amount of time or pay actual money. In spite of the fact that keys are a secondary kind of currency in the game, they are an essential item that may be used to revive characters after they have been defeated. As a result of the fact that the price of revives goes up after each failure, it is absolutely necessary for players to save as many keys as they possibly can.