Storing leftover canned pumpkin puree is crucial to maximize freshness and avoid spoilage. It is best to transfer the puree into a sterile, airtight container within two hours of opening the can. The puree should be stored in the refrigerator and can last for three to seven days. Alternatively, you can freeze the puree to make it last longer. Various ways to use pumpkin puree before it spoils include adding it to coffee, making smoothies, stirring it into yogurt, using it as a sauce for pasta, or using it as an egg substitute in recipes.