Pathfinder Society has some guidelines to encourage fair, respectful play. I encourage you to read the full Community Standards and Expectations page.
No Evil Characters
Evil characters are not allowed.
Pathfinder Society features characters who are members of the in-world Pathfinder Society, which lives by the motto “Explore, Report, Cooperate.” Characters who don’t play well with others won’t last long.
PFS uses a system called “Infamy” which creates a sort of “three strikes” system for characters. Evil acts, criminal acts, and specific actions called out in scenarios can see your character gain Infamy. Each point lowers your effective level by 1 when acquiring items, which is itself a huge penalty. If your character gains 3 Infamy, they’re ejected from the Pathfinder Society. In effect, they’re dead.
If you do acrue some Infamy, you can spend Achievement Points to purchase the Untarnished Reputation Boon. However, this requires that you reach Admired, which requires something like 15 games with that character, and you’re spending 12 Achievement Points (as much as you get from 3 typical play sessions) to pay off bad decisions instead of fun things like unlocking rare ancestries.
Playing evil characters can be fun in the right game, but Pathfinder Society isn’t the place for it.
Rules Changes, Interpretations, and Restrictions
Over time, there will be errata. Sometimes that will mean changes to feats, items, etc., and if that affects your charatacer you may need to make some changes as described in the Rules Changes section.