With a a few exceptions, and if used in accordance with the owner's manual, scooters generally do not require maintenance or regular service.
Scooter batteries do wear out. Signs of battery wear are that the scooter just doesn't travel as far or keep a charge as long as it did when new.
Tire tread wear is normal over time. The tread on most scooter tires, with the except of air filled pneumatic tires, is more cosmetic than functional. (See related article).
Occasionally, a scooter (Particularly Drive models) may need some light dusting or a wipe with rubbing alcohol to wipe any debris off between the scooter battery and battery platform or on the metal contact prongs between the front and back sections of the scooter.