This thread is designed to give those who are looking to prevent their Delta Air Lines SkyMiles from expiring, with the list being updated with the latest information here in this milepost. How to keep your Delta Air Lines SkyMiles from expiring: Fly on a Delta Air Lines or Delta Connection flight. Fly on a SkyTeam or Delta Air Lines partner airline. Patronize a partner of Delta Air Lines, whether it be via a hotel, car rental, shopping or other partner. SkyMiles Dining (part of the Rewards Network) Use of a co-branded Delta SkyMiles American Express credit card Miles redemption - minimal amounts for items such as magazine subscriptions will cost as little as 500 SkyMiles, but will extend miles another 18 months.