I’m not saying you should carry the strong key on a piece of paper.
I’m saying you should use one single strong key that you remember, and use that to protect your other secrets such as your encrypted files and other passwords.
Since that one single strong key is the key to ‘everything’, it’s pretty bad to lose, therefore you should have a non-perishable backup safely stored away. Our suggestion is a piece of paper in a safety deposit box or similar.
Our suggestion is that you keep the entire strong key in your memory, and keep a safe backup of it.
We provide our smart password generator that creates strong, but useful, passwords to assist you. Try it out here: https://www.axcrypt.net/password-generator/ . It’s of course included in our password manager as well.