Due to their high fat content, nuts can turn rancid, especially once they’ve been shelled. When stored in an airtight container in a cool, dry place, most unshelled nuts keep for up to a year (walnuts and pistachios, up to 3 months). Store shelled nuts in an airtight container in the refrigerator for up to 4 months, or freeze for up to 6 months. Since they contain almost no water, there’s no need to thaw nuts before chopping, eating, or cooking.