Pepperoni does expire, but it is often still good to eat for 2 to 3 weeks after its sell-by date if kept in the refrigerator. Pepperoni can be stored 6 to 8 months past its sell-by date in a freezer.
The sell-by date is not an expiration date but rather the day that the store must sell it buy. In order to maximize the shelf life of pepperoni, it is important to refrigerate or freeze it immediately and to store it in an airtight container. If the pepperoni starts to feel slimy, changes color or smells sour, it is time to throw it out.