If your bacon is in its original sealed package, you can go by the expiration date listed on the package. If you've already opened the package, make sure to cook up the bacon within 1 week of opening to be safe. (Confession: I've used bacon more than 1 week after it's been opened, but the comfort level is up to you.) If at any point your bacon starts to change color or smells off, it's safest to discard it.