The Zettelkasten approach doesn't require memorization at all, it is assumed that you will keep working with your notes forever and they are the memory. But it

The Zettelkasten approach doesn't require memorization at all, it is assumed that you will keep working with your notes forever and they are the memory. But it also emphasises putting each idea on its own note, paraphrasing into your own words rather than merely copying, and thinking deeply about other notes and topics you already have that the new note might relate to. And that has to help with remembering them.