I have used OnSong on a family member's AppleID. How can I use it on my new account?

I have used OnSong on a family member's AppleID. How can I use it on my new account?

While you can download and install OnSong on any device that's associated with the AppleID of the original purchase, you can't transfer the purchase to another AppleID.  However, if both AppleID accounts are associated with the same credit card such as in a family, you can sign up for App Store Family Sharing.  This will allow you to install OnSong on the other account free-of-charge.  However one limitation with Family Sharing is that in-app purchases are not able to transfer between accounts.