Sliced pepperoni should always be refrigerated. But, a pepperoni stick (whole pepperoni sausage) does not need to be refrigerated unless that's specifically noted on the packaging. Unopened pepperoni sticks can last indefinitely in the refrigerator and for up to 6 weeks in the pantry. Once opened you should enjoy the pepperoni within 3 weeks. Unopened sliced pepperoni in the refrigerator lasts a week past the best-by date. But, once opened, you should eat it within a week.