Frequent flier account balances can be zeroed out for inactivity. But there are cheap, easy ways to avoid this from happening. And they don't require flying.
During the past decade, most airlines instituted mileage expiration policies for travelers who don't have some type of activity on their account within a certain time frame, generally one year to 18 months. Flying is the most obvious way to earn miles. But travelers often overlook everyday activities that earn or use miles, in turn preventing mileage balances from going "poof!" (Read more: Frequent Flier Miles Vanished? Here's How to Get Them Back)
Here are my tried and true methods to ensure my frequent flier account balances never expire.