Problem with In-App Purchases.

why this is so in app purchase is not available … check your internet connection settings or try again when my internet is gone

Are you sure you are connected to Internet.

Also what device and OS are you using.

Helpful tips:
Restart Infinite Flight
Restart Your device
Turn your internet off and on.
If worse comes to worst, delete Infinite flight and reinstall it

Please contact support@infinite-flight.com if this persists.