Everything is trying to sell you "memory hacks" with a 19.99 subscription and pastel UI. You don't need it. What works is short daily recall and spacing, which is miraculously free if you make your own cards. The cost is time and a little boredom.
I'm mad I learned this after paying for a course that mostly read slides back at me. Now I set a 10-minute timer, quiz myself from a tiny stack, and stop. If I miss a card twice, it goes to tomorrow; if I nail it, it waits a couple days. Library printer for a dozen index cards beats another subscription. If you need an app, use a free one with spaced intervals, but don't pay to procrastinate.
