How can you retain forever what you learn?
Spaced Repetition (based on SM2 algorithm) will resurface notes based on how well you remember their contents. It might be tomorrow if you don't remember much or in 6 months if you could recall all of it. You can also use various predefined static patterns (like 1, 5, 15, 30 and 60 days)
Set Recall Questions for your notes & highlights
Try to answer the question about your note/highlight to strengthen neural connections in your brain significantly. Use easily accessible Study flow based on tags/books/notebooks to go through the whole deck in minutes.
Track your memory over time
You can always see your memory state and react with Quick Actions on your Dashboard. Use Priming Effect (wallpapers from notes on autopilot) to nudge yourself with valuable insights.
NeuraCache is shaping the way we think about structuring easily-accessible (cached) graph of knowledge in our mind.