Why am I required to repurchase this app?

I first purchased this app from the App Store when I got my iPhone 3S back in med school. It loaded onto my iPad with no problems back in early 2013. I recently replaced my 3S with a 6 and Im receiving instructions to purchase the app. Unbound rep said they couldnt help because I purchased it through the App Store, not from unbound directly.

This is also an issue with several other apps...shady!

jmmacko about Diagnosaurus® DDx