Ceiling fans should last from 8 to 10 years with a lot of use.
I've replaced a ceiling fan that was 30 years old when it finally gave out and needed replaced but I don't know how much use the ceiling fan got because It was in a house I had moved into 3 years before the ceiling fan gave out.
But with today's ceiling fans I wouldn't expect them to last longer than 10 years and it could need replaced sooner if you leave the ceiling fan on a lot.