Homemade s’mores cereal bars can be stored at room temperature in an airtight container for up to 3 days. If you want them to last a bit longer, store them in the refrigerator for up to one week. Be sure to wrap them individually or store them in an airtight container so they remain fresh and delicious. If you make a large batch, you can also freeze some of the bars for up to three months. Just remember to let them come to room temperature before serving for the best flavor and texture.