jm % ÁÕÖòÆ:5çNæëEyªÌ÷CWó*Ñ OymL©BIP39 mnemonic should be provided to the user and forgotten. The Memo password should encrypt the XPRV for this specific account and should be unlocked on each session.
https://whatsonchain.com/tx/aa5b0a14203ab109958fc588ebe815b8e4e68c28999ea671c6b3d4b85b0c586d