Brake pads should last from 70,000 to 100,000 miles and sometimes even more miles but it all depends on how often you use the brakes to stop the vehicle.
If you do mostly highway driving with less stopping then your brake pads will last much longer but if you do a lot of stop and go driving or ride your brakes a lot then the brake pads will wear out much sooner.
If it's been 70,000 to 100,000 miles since you've replaced your brake pads it would be a good idea to inspect the brake pads or have the brake pads inspected just to be safe.