I read earlier that while coffee grounds have a limited shelf life, instant coffee is good for more than a year past it's "expiration date." I've found that to be true.
FYI - I treat "best by", "best used by", "expires", etc. as almost irrelevant in most cases. Since when does bottled water have an expiration date? Freeze meats as soon as I get home so they can be used later. Please note, if it's iffy, I pass it by.