If you're not using a password manager now, that implies you're already remembering at least one password. Using it on a regular basis is a good way to keep it

If you're not using a password manager now, that implies you're already remembering at least one password. Using it on a regular basis is a good way to keep it in your head. You can setup your password manager authorization to expire periodically (eg, every 30 days) as well as on reboot. With LastPass (probably others) you can also mark certain sites as 'high security' and require entering your master password again. I do this with a small handful of sites, including my bank and domain registrar. I typically log into my bank once or twice a month. I very rarely reboot my devices (sleep + locked with a different password I have memorized and type in) so I don't get prompted for it that much otherwise, but enough that I have it memorized.