Butter does not have an infinite shelf life and does expire. If unopened butter is refrigerated at temperatures below 40 degrees Fahrenheit it can last up to two months. Butter that does not contain oil only stays good in the refrigerator for one month.
Butter that has been frozen can stay good for six to nine months. Butter that has gone bad has a pale appearance. Butter does not have to be refrigerated, but refrigeration extends its shelf life.
Butter is made from cream or milk that is churned until it turns solid. The cream or milk usually comes from cows but may also come from sheep or goats.