If the target creature becomes an illegal target before Unlicensed Disintegration resolves, the spell is countered. No player is dealt damage.

If the target creature is a legal target but isn’t destroyed by Unlicensed Disintegration, most likely because it has indestructible, Unlicensed Disintegration still deals 3 damage to the creature’s controller.

Whether or not you control an artifact is checked only as Unlicensed Disintegration resolves, after the creature is destroyed. For example, if you destroy a Fairgrounds Warden that exiled your artifact creature, Unlicensed Disintegration deals 3 damage to Fairgrounds Warden’s controller.