A few of my friends are working on getting licensed. None own planes and will be renting them as needed in the future. That is a great question. Some people never give it a thought. The following is an explanation of the Federal Aviation Administration requirements.
All aircraft require periodic inspections.
One type is done annually, and consists of a thorough inspection of everything mechanical and electrical in the aircraft. It must be done by a certified mechanic, and signed off as completed and reviewed by a certified aviation inspector. Some systems on the aircraft require calibration and checking periodically by a mechanic licensed properly. These include checks of the the sirspeed and altitude indicator systems and the transponders used to enhance radar returns for Air Traffic control. In addition, the pilot in command must do a thorough pre-flight inspection and determine that the aircraft and all systems are airworthy and safe.