How to create Stamina system in role-playing game

I want to make the stamina system for entering each dungeon.

The stamina will recover although player closed the game.

how can I do??

To prevent cheating that system, you'll need a back end web server to host persistent data while the client is not running, and sync with client when they log in.

Otherwise, you might be able to do something by parsing out system time, but a user can just change that on their own system.