Monthly plans for all courses and curricula. Unlimited = read all*; Unlimited+ = read and practice all*. Certification stays per course.
To remember longer, you need spaced review and mixed practice. Study in short sessions, re-check after a delay, and practice retrieving answers (not just re-reading notes).
These two techniques are consistently effective.
Do a short practice set today, then do a smaller refresh set later. If you miss a question, use that miss to choose tomorrow’s practice.