You can store butter at room temperature, in the freezer or in the refrigerator, but each storage method has its own unique shelf life. Butter stored on the countertop can sit out for a couple of days in an airtight container, while butter in the refrigerator can last until its expiration date. Frozen butter should be in an airtight container and can stay fresh for up to four months, then used within 30 days of thawing.