When first installing the game, you will start off with 2 Passes.

Once you have used these Passes, a countdown timer will appear. This is the time remaining before your Passes regenerate back to 2. You can decrease your wait time by watching an ad, to do this select the green play button at the top of the screen.

You can also gain 1 free Pass every 24 hours by watching an ad in the Passes store. Other than this, Passes can be purchased in the store.