They must be used by the time you level they do NOT rollover. Also they do not refill till you gain a new level. So use em or lose em
You can spend an action point to improve the result of an attack roll, a skill check, an ability check, a level check, or a saving throw. Certain feats and prestige class features allow you to spend action points in different ways, but this is their most basic use. When you spend an action point, you add the result of a roll of 1d6 to your d20 roll to help you meet or exceed the target number for the roll. You can declare that you are spending an action point after you have already rolled the d20, but you must do so before the Dungeon Master reveals the result of your roll (whether the attack roll or check or saving throw succeeded or failed). You can’t use an action point on a skill check or ability check when you are taking 10 or taking 20. You can only use action points once in a round. If you spend 1 or more action points on a special action (see below), you can’t spend a point in the same round to improve a die roll, and vice versa. No spell, power, or other special ability can allow a character to reroll an action point die. If a character suffers permanent level loss, he does not lose any action points he has remaining, and any subsequent level advancement provides new action points as normal.
Instead of altering the result of a d20 roll, you can use action points to perform one of the special actions described below. In addition, some
prestige classes and feats allow you to spend action points to gain or activate specific abilities.
Activate Class Feature: You can spend 2 action points to gain another use of one of the following class features that has a limited
number of uses per day: bardic music, rage, smite evil, Stunning Fist, turn or rebuke undead, or wild shape.
Hasten Infusion: On his turn, an artificer can spend 1 action point to imbue an infusion in 1 round, even if the infusion’s casting
time is normally longer than 1 round.
Stabilize: When your character is dying, you can spend 1 action point to stabilize at your current hit point total. Spending an action point does nothing for you if you’re already dead.
Attempt difficult maneuvers: You may try something that might not normally be allowed or doable if they are high action [Up to my call]
Saving throws You may use an action point to aid a saving throw roll.
Skill check You may add an action point to any single skill check, or use an action point to reroll a failed one.
Extra attack you may use an action point to gain an extra attack at your highest attack bounes. This must be used as part of a full attack action