It's always good practice to securely close your wipe box or package after each use. If you leave it open, you are prone to finding yourself with dried-up wipes. While it typically will only affect the next wipe in the package, doing so for a long period of time will leave you with an entire dried-up package.  While baby wipes do technically expire, it's not for about two years. At that point, they will start losing their moisture and won't be as effective at cleaning. If you're in a pinch, you can always try wetting a dried-up wipe for a quick clean-up.