I pay a monthly fee charged every 3 months on a CC with access online 24/7 to all that is available whether history, archaeology, arts, science, etc., and so much more. I don't know the monthly fee for the US subscribers. The fee is not supposed to increase if one maintains the subscription but may be cancelled readily.
Some are short courses for a single session, some have 6 sessions, some 24 -36 sessions. Most sessions are 30 minutes in duration. The basis, I believe, is the 13,000 courses from "The Great Courses" https://www.thegreatcourses.com presented by college professors within in their field of expertise. Added options from other websites such as Craftsy, documentaries, health info sessions make it quite a diverse, interesting source of education and info.
If I had had the option I would have been a professional student all my life. This gives me that option, fits my timetable and interest at a very modest fee.
There was a promotion at one point for C$10/month and I loved the courses that I had ordered from The Great Courses so I subscribed. I love it!