Put this in the file marked “Why Frequent Flyer Mile Expiration Policies Have Become More Strict.” Rocky Mountain News reports from a recent JPMorgan Chase & Co. transportation conference in New York that United Airlines expects to gain a one-time benefit of $170 million this year from its move to tighten expiration policies covering frequent flyer miles. Jake Brace, United’s chief financial officer, also conveyed, “The growth opportunities tend to be international — we don’t think that it makes a lot of sense to add capacity in the domestic market.” So, look for more international flights in United’s future.