Award miles in the Miles & More program (the frequent flyer program for Lufthansa, Swiss, Austrian, and others) are typically valid for 36 months from the date they are earned. If the miles are not used within this three-year window, they expire at the end of the respective quarter. For example, miles earned on December 12, 2023, would expire on December 31, 2026. However, there are several ways to achieve "mileage protection" and prevent expiry. If you hold frequent flyer status (Frequent Traveller, Senator, or HON Circle), your miles will not expire as long as you maintain that status. Additionally, holders of a Miles & More Credit Card in many countries enjoy mileage protection, provided they make at least one miles-earning purchase each month and have held the card for a minimum amount of time. You can track your expiring miles through your online account statement or the Miles & More mobile app, and the program typically sends a summary in their newsletter two months before any miles are due to lapse. Once miles have expired, they generally cannot be reinstated, so it is crucial to keep an eye on your balance if you do not have status or a co-branded card.