United changes mileage expiration to 18 months

Based on this press release from United Airlines, the company will be requiring that you fly on their airline (or a partner airline, but use your United FFN) every 18 months to keep your account active, instead of the 36 months it was prior to the release. There are other ways to keep your account active, such as signing up for a credit card from United, giving away miles, or using miles, but it's something to keep in mind.