The Battle Pass in Mr Autofire is a series of rewards you can earn by collecting Season Points. Each Season lasts for 28 days, and each Season has its own Battle Pass.

Free Pass and Battle Pass
Everyone has access to a track of free rewards in the "Free Pass". Optionally, you can purchase the Battle Pass to unlock the opportunity to earn additional rewards.
Please do note that the seasonal bonuses (i.e. increased energy cap and Battle Pass stat bonuses) only apply for the duration of the Season.
Earning Season Points
You can earn Season Points by completing Tasks. There are two kinds of Tasks: Daily Tasks and Season Tasks. Daily Tasks refresh every day. Season Tasks can be completed until the end of the Season. However, not all Season Tasks are open in the beginning of the Season. Instead, a new batch of Season Tasks unlocks every week.
Buying the Battle Pass
You can purchase the Battle Pass that grants access to the Battle Pass rewards as well as additional unique benefits by tapping on the "Get Battle Pass" button on the bottom left of the screen.
You can purchase the Battle Pass any time during the Season. As soon as you purchase it, you can immediately claim any rewards you may have already earned in the Battle Pass track.
The Battle Pass purchase lasts until the end of the Season.