Where can I use the purple key of subway parkour?

The purple key of subway parkour can be exchanged for props, skateboards, characters and other items in the store's treasure-winning interface. Purple keys can be used on some specific purple doors. You can get more gold coins and props after entering the Purple Gate. The Purple Gate is generally difficult to find, and it needs to be reached through various jumps and climbs, which increases the difficulty and boredom of the game. In addition, there may be some unusual hidden tasks and challenges hidden in the Purple Gate, which require players to concentrate on exploring and decrypting.

Please note that the above answers are based on hypothetical situations, and the specific usage and functions may vary according to the game version or the developer's instructions. Please refer to the official instructions of the game developer.