In "Tuesdays with Morrie", Mitch Albom writes about the last class of his old professor's life. Why does Mitch refer to the book as "a last class", and what is significant about the set up of the book?

For the answer to the question above, the last class of my old professor's life took place once a week in his house, by a window in the study where he could watch a small hibiscus plant shed its pink leaves. The class met on Tuesdays. It began after breakfast. The subject was The Meaning of Life. It was taught from experience. It took place in Morrie's little house right outside of Boston.