If Decommission destroys a permanent you control, it will enable its own revolt ability and you'll gain 3 life.

If the target artifact or enchantment becomes an illegal target, Decommission is countered and none of its effects happen. You won't gain life.

Revolt abilities check only whether a permanent you controlled left the battlefield this turn or not. They don't apply multiple times if more than one permanent you controlled left the battlefield. They don't check whether the permanent that left the battlefield is still in the zone it moved to.

Revolt abilities don't care why the permanent left the battlefield, who caused it to move, or where it moved to. They're equally satisfied by an artifact you sacrificed to pay a cost, a creature you controlled that was destroyed by Murder, or an enchantment you returned to your hand with Leave in the Dust.

Tokens that leave the battlefield will satisfy a revolt ability.

Energy counters aren't permanents. Paying won't satisfy a revolt ability.