Leftovers: Leftover crumpets can keep at room temperature for 2-3 days if they are sealed in an airtight container. However, they will stay the freshest if they're frozen after being cooked and cooled. Freeze: Seal them tightly in a zip-top freezer bag, pressing out the extra air and freezing for up to 1 month. There' s no need to defrost before toasting.