I am notoriously forgetful. I make multiple lists and heavily rely on post-it notes. Frankly, I do everything except tie a knot on my finger, though I have never really understood that anyways. It's not like it tells you what you need to remember - just that you need to remember something. What I would do is wear one of these charming knotted or braided leather rings from By Boe. Sure, they may do nothing for my memory but at least my fingers will look cute.