Like it,but – Core Curriculum Third Grade Review

I used this App with the child that I mentor. He liked it, he was successful with it, it was right where he needed to be challenged as far as reading. But when I tried to purchase some of the other subject areas, it says that the in-app purchase ability is been disabled. How do I fix that? I did not turn it on.
Review by Reading Inc. on Core Curriculum Third Grade.