Often, companies will only certify their products for a certain amount of time. This doesn't mean that they won't last longer, just that the company has not taken the time to test their product to see if they will last longer. Your test strips are probably fine if they were not opened. The expiration date is just for liability reasons. If you do get a bad reading after the exp, they don't want to be held responsible.
...You know, legal stuff!
