My ewallet is very old, over 60 years, but I retain nearly all number numbers in my memory. That works, Sadly I don't remember my wedding anniversary, but Mrs. jb seems not to care because I always remember her birthday.

Seriously I keep all my numbers in SplashID together with login data and credit cards. That has been easy and useful since ancient PalmPilot days. It does not have the slick images and bar codes of the iphone apps though. I have never needed those...