You can use your brain to remember the password and record it on a paper notebook or a computer without an Internet connection, but remember to save it. Once you lose it, your wealth may be discovered by others.
Don't rely on your "brain"(memory) to remember the password. That's is the worst mistake you can make. No matter how good your memory is, don't forget, as you age, you brain starts to deteriorarte (cells slowly dies) and your memory won't be as sharp as it used to be. You will end up either forgetting or mixing up everything and then there goes your fortune. Use your memory, and keep multiple backups, digitally and offline in a safe and secure place!