Purchased App but not available for download to iPhone

I purchased this app a few days ago while using my iPad. It worked great & seemed to be my best option for RDP. But when I go to the App Store in my iPhone to download this app, it is not showing as available to me in the cloud. If I download, I will end up paying for the app again. ?????

Alaneylou about Remote Desktop - RDP, v3.7