Update Windy on iPad Air iOs 12.5.7

[Schluppy]

Hello,
I´m using Windy Premium on an iPad Air with iOS 12.5.7 (can´t get newer one) and get the request to update the App
otherwise it will become obsolete.
What does this mean? Does this Windy App no longer work on this iPad?

And how to update? I can´t find any bottom nor any update mark on the App Store.
Can any body help me with updating my Windy Premium?
I am a sailor on a small boat and Windy helped a lot sailing the North Sea and English Channel.
Thank you for your help, nice greetings from Germany.
Schluppy