Since march 2018, unlocking the evaluation of Fly Is Fun is done via in apps subscription. Since new user should NOT subscribe to FLY is FUN unlocker !!! They DON'T NEED IT !!!

Then why keeping FLY is FUN unlocker on line in the store?
FLY is FUN unlocker is there, only to allow users that bought it before to unlock FLY is FUN when they install the application on a new smartphone or tablet, without having to subscribe again.
In march 2019, since in application subscription will be there since 12 months, FLY is FUN unlocker will be suppressed and users will have to subscribe via FLY is FUN in application option

Enjoy FLY is FUN and have safe flights