I bought this for my six year old daughter to use. We have family sharing, so I bought it on my account (daughter can’t make purchases), then installed the games on her iPad.
Issue 1: This normal purchase/install apparently doesn’t work because you will find help sites of people asking why their games are in demo mode. There is a complex fix for this, which I did.
Issue 2: The complicated fix can break! After doing he whole thing once, now I have to do it again!
Issue 3: these games are just games with an occasional interruption to answer a trivial math question. The game learns VERY slowly what level your child is at, so the entire time I watched my daughter play these games, she was answering math questions that were super simple for her.
Don’t waste your time (and you may spend a ton of time uninstalling and reinstalling, deleting accounts and changing owners of your devices) or money. Find something else.