Dear Cashing In,

I no longer have an AAdvantage credit card. How do I keep my American Airlines miles from expiring? 

-Sylvia

Dear Sylvia,

Like United, US Airways and Frontier Airlines, American Airlines' miles expire after 18 months if there's no earning or redeeming activity on the account. Without activity on your AAdvantage credit card, which kept that account active, you have several options for renewing your account without actually flying.

Using the AAdvantage dining program is one way. You register up to six credit cards in the program and then pay with one of them when you eat out at one of the thousands of participating restaurants. Points are automatically credited to your account.       

Shopping online via the AAdvantage shopping portal is another way. Purchasing a $1.29 song in iTunes through the portal is all it takes to renew your miles account for another 18 months.

If you book a hotel room from a partner of American Airlines (including any hotel under the Hilton, InterContinental or Starwood umbrellas), you can credit the miles to AA, or you can transfer points from those hotels' loyalty programs. You can also earn AAdvantage miles when you rent a car from one of the airline's partners (Avis, Hertz and Budget, among them).                 

As with most airlines' frequent flier programs, you can also buy or gift miles, redeem miles by subscribing to a magazine or donate miles to any of American's partner charities. Any of these activities will renew your account for another 18 months and can be accessed via the AAdvantage website.

With the exception of Delta, whose SkyMiles never expire, most airlines require you to use (or lose) your miles now and then. Miles on Southwest and Alaska airlines expire after 24 months of inactivity. British Airways Avios miles expire after 36 months. 

Most airlines also offer options similar to American's for keeping miles active, with some variations on the theme. United, for example, partners with most of the same car rental companies as American and several of the same hotel chains, including Hilton, Starwood, Hyatt and Wyndham.

MileagePlus, the United frequent flier program, also has its own dining program and shopping portal. If you happen to have a Chase credit card that earns Ultimate Rewards points, you can transfer them to United to keep your account active. And United is the only airline that gives you mileage credit for buying a ticket on Amtrak

Southwest Rapid Rewards has its own dining program. You earn 300 bonus points for your first $25 in dining. Rapid Rewards also lets you transfer hotel points from Hyatt, Marriott, Choice or Wyndham, as well as several rental car companies.

See related: Cheap ways to keep flier miles active