Using AS images to illustrate a book

I would like to use AS images for a book that would be sold commercially.  The images would support the content of the book rather than being the primary focus (like images in a textbook).  I've read through the contract information regarding licensing and it is a bit unclear to me.  I have also read through a thread from 2016 which I feel answers my question; however, as it is 2 years later would like to re-verify the answer in the event something has changed.

From what I understand, AS images can be used in a book under the standard licensing agreement as long as printed copies of the book do not exceed 500,000 copies.  If I wanted rights to print unlimited copies I would have to purchase an extended license or purchase another standard license if printed copies exceeded 500,000.

Thanks for you time in answering my question.