Recovering my lexulous license.

I bought lexulous from the apple store, then bought a license to stop seeing ads on my iPad. One day I deleted it by mistake. I downloaded it again for iPad, but now I can’t recover my original license. I wrote lexulous about this. They told me I had to recover my license through apple. If that’s true, Apple makes it too hard for a geezer like me to find out how to recover the license I paid for. Any help is much appreciated.