I wasted $2.99!!

I have ios7 and I was looking for a custom keyboard app, and I found this. When I finally got the$ to get it, I was happy. Then in the app I saw "you need to upgrade to iOS 8 to use outside of this (the keyboard) app"! I cant get iOS 8! You either need to fix this or do something for me, please.

ianjs36 about KeyThemes - Themed Keyboards