Think about it this way. Hops are harvested once a year. So the hops you have are (hopefully) from the harvest last summer. So they are as fresh as the hops in your LHS, with the only difference being how they were stored.
Temperature and oxygen are the enemies.
Now days, with Australia and New Zealand in the hop business, you can find imported hops in the off season, so they could be fresher depending on the time of year, but only if they have been shipped and stored properly.
So to answer your original question, store them properly, and a year or more is not unusual.