AP is earned through Battle Quests and the Meditation Skill. Players can also get AP through AP Capsules that can be give through events, Level Up rewards, or NX Items. A character can an unlimited amount of unspent AP.
Here are a few examples of ways to earn AP:
1. Daily Temporal Missions will sometimes have AP capsules as rewards.
2. Secret Boxes and Warm Welcome Boxes bought from the Strange Traveler.
3. Through battles.
4. Guild Seal shop and other various event coupons.