I use this calculator on my iPad 3, https://itunes.apple.com/us/app/calculator-for-ipad-free/id398129933?mt=8. It's an excellent calculator so I paid to remove the ads from the app for $1.99. Recently I restored my iPad to new state then re-installed this calculator. But now the ads are back. Are in-app purchases not saved? Do I have to pay $1.99 again?
Read the FAQ on the developers website:
Retrieving data ...