Dairy products are easy to spoil, except butter. And how long butter can be stored still depends on its specific storage condition. If you have package butter, the printed expiry date is usually 3 to 6 months. And an unopened pack can last for about one month past the printed date. Butter can also be frozen to further extend its storage life, to even six to nine months more. However, if you put it in a container, butter will only last two to three weeks.