if you are short sighted - like me
then it should last all your days!!! (if you ahve a stable prescription, some peoples eyes get worse over time, so if you ahve to keep getting a new prescription, it's probably not going to be much help)
ALso, as you grow older the muscle in your eye weakens - hence why people need to get "readers" to read things close up
I would need to get prescription readers if i didn't have surgery - as anything with a minus prescription must come from an optometerist.
However, after surgery, if i need readers i can pick up the ones form a chemist as they are all magnifiers (a + prescription) and can be bought over the counter
my prescription has been stable for years now, but that doesn't mean i won't need readers in a few years. just means i'll only need one pair of glasses rather than changing pairs constantly.