This app is annoying!
Seat alert search apparently has a limit on the number of times you can search for a free flight. After searching a flight less than ten times, it suddenly just refused to work and told me that I needed to pay for subscription if I wanted to continue searching. Fair enough. But then, after waiting for more than 12 hours, the app still refuses to work! If you really need to check the availability of a flight, I suggest you look elsewhere.