You can still eat expired chips.
Chips that are expired may not taste as good as fresh non expired chips but as long as the expired chips have remained sealed the expired chips are safe to eat.
As long as the expired chips don't have any mold or really bad taste to them you can safely eat the expired chips.
There's a discount food store hear in my town that sells foods that are near expiration date or have expired but are safe to eat.
I buy canned foods that are expired or about to expire and even chips that are about to expire or have expired.
I've eaten the expired chips and other expired food and never have gotten sick from it.
While it's best to eat the chips before expiration date you can safely eat them.
When chips have gone bad they will taste really bad and then you wouldn't want to eat them.
Usually though if the chips are only a year or less expired they are still okay to eat.
Once opened a bag of chips will go stale within a few days if you don't seal the bag back up.
Once you open a bag of chips you should use a chip bag clip to seal the bag up.