Expire History by Days is a Firefox add-on designed to help users manage their browsing history effectively. This subscription-based tool focuses on enhancing security and privacy by allowing users to set specific expiration times for their browser history. The add-on functions by expiring history entries based on user-defined time frames, ensuring that older data is automatically removed from the browser. The expiration process occurs during idle times, although the initial expiration may temporarily block the user interface, with subsequent expirations being less intrusive.

It is important to note that the add-on overrides the default Places expiration system, which is optimized for performance. Users are warned that utilizing this functionality may lead to unexpected performance issues and is not necessary for most users. Therefore, it is recommended only for those who have specific needs for managing their browsing history in this manner.