How can one know how many of the 108 lives he or she has left?
Only from your Inner Being, through dreams, visions, experiences, etc.
Each person has their own karma. That is not measurable by any intellectual system.
Nevertheless, generally speaking, everyone on the planet is at the end of their 108 lives.
Only from your Inner Being, through dreams, visions, experiences, etc.
https://gnosticteachings.org/courses/prophecies-of-the-days-to-come.html
https://gnosticteachings.org/courses/prophecies-of-the-days-to-come.html
https://gnosticteachings.org/courses/prophecies-of-the-days-to-come.html
I believe that is specified in his lectures, not books, but I did not find a reference for it.
Read these books:
https://gnosticteachings.org/books-by-samael-aun-weor/the-aquarian-message.html