FLY is FUN

I have been a user of fly is fun for 18 months now and am very impressed by the application. Today, across all screens in large letter is the statement "Trial to continue navigate close and restart application." I have done this but the message remains blocking half the screen. What is the cause of this and how can I remove this message?

Try to upgrade FLY is FUN unlocker...

Thanks for the advice. The application seemed to sort its self out. The message has gone. If it re-appears I will update the unlocker.