Can anyone explain Amazon App Store issue?

I've been utilizing iRealPro on my Android device for a while, but recently, whenever I tap the app icon, a message appears informing me that I don't possess the app and recommends downloading it from the Amazon App Store. After following this suggestion and installing the Amazon App Store, it prompts me to purchase iRealPro again, despite having already paid for it. Can anyone explain what's happening?

We presume you are signed in to the Amazon Account you used to purchase the app. If so, and you still have problems, try a reboot.
Otherwise please contact Amazon directly, they can check your account details, verify purchase and help with problems.