Every AIRWORTHY aircraft has to undergo a mandatory annual inspection as a pre-requisite for renewal of its Certificate of Airworthiness & Certificate of Registration. An annual inspection will include compliance of the manufacturer's Service Bulletins (SB's) and Air Worthiness Directives (AD's) as well as defect rectification called for by the aircraft safety inspector. This is to ensure the safety aspect of the aircraft at all times. Aside from the annual inspection, periodic maintenance inspections are carried out by the Aircraft Maintenance Organization Service Provider or their duly approved Maintenance Department. Such is the 50 & 100 hour check. Larger aircraft have to do a mandatory inspection every 20 years. Some will have to undergo an IRAN (Inspect & Repair As Necessary). All aircraft engine types has a given life span or what we term TBO (Time Between Overhaul), which are properly monitored and logged after each flight for immediate reference and traceability. Once the engine nearly reaches its manufacturer's limit, say for example 1500 Hours, this has to be pulled out for replacement or overhaul (OH). That is even if the engine shows no signs of visible wear. That's how stringent aircraft maintenance is.
Unlike cars or trucks, most of us wouldn't even care to check or maintain our engines properly and would continually using it to a bitter end. Well, atleast you can just park your car by the roadside if the engine conks out. I don't think we can do the same for an airplane on flight.