Homemade toffee can go bad, but it has a relatively long shelf life if stored properly. Typically, it can last for several weeks. To extend its shelf life, store the toffee in an airtight container in a cool, dry place. If your home is warm or humid, you might consider storing it in the refrigerator. Toffee's quality may decline over time, becoming either too hard or too soft, and its flavor may also change.