Yes sterile water does expire and the sterile water you buy should have an expiration date on it.
Once the sterile water gets past it's expiration date then it's not considered to be effective anymore and if you're using the sterile water for bladder irrigation or use in any other body organ then the expired sterile water should not be used.
If you're gonna use the sterile water for something such as nasal irrigation then it would likely be okay to use it past it's expiration date.
Also drinking expired sterile water would be okay as well but you could boil the sterile water after expiration date and make it sterile again.
But if you buy the sterile water it's best to use the sterile water before expiration date.