APP Problem

[ohhyeababy]

I am an owner of an iPhone app, I have been getting emails from people saying this.........

Message: I upgraded to the iphone6 and when the app was loaded onto my phone, there is no way to input my info to bring my subscription back that I already paid for. How do I get it back?

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Any idea how to solve this? I upgraded to the new iPhone too and have the same issue..