If I understand correctly this patent is only active in the USA. Anki is based on SuperMemo-2 and they freely admit it. SuperMemo (based in Poland) has pretty l

If I understand correctly this patent is only active in the USA. Anki is based on SuperMemo-2 and they freely admit it. SuperMemo (based in Poland) has pretty liberal licensing: https://www.supermemo.com/en/blog/licensing-and-copyrighting-of-supermemo-algorithms https://www.supermemo.com/en/blog/licensing-and-copyrighting... I can't see this patent holding up unless it's for a very specific flashcard system. There is prior art on flashcards going back to the 19th century.