I found I have brainspace for ~15 passwords. All complex - non words greater than 8 characters. Though, as I get older.. I can feel this ability waning. Thus I

I found I have brainspace for ~15 passwords. All complex - non words greater than 8 characters. Though, as I get older.. I can feel this ability waning. Thus I am interested in using a password manager - though I feel a little uncomfortable about it as I have never used one before.