This is a common misunderstanding with a google device. Items purchased are only available when the purchasing account is active on that particular device. I think you discovered this the hard way. You can set the pin so that purchases cannot be made on that device, but there will still be acess to other information such as emails, browsing history, purchases, etc. If you want to extract the pinned files from one account with a file manager and insert them manually, we can help you. It is kind of tricky unless you are quite familiar with the android system.