[ The question earns a quizzical look of its own. Running into someone who doesn't have a grasp on androids is...jarring. Almost everyone knew about such details where he's from. ]

The most basic requirement is a substance called Thirium, but it doesn't need to be administered unless the android has received some kind of severe physical damage. If they manage to avoid being damaged, androids are self-sustaining throughout the entirety of time they are in use.