The University/College Library has over 250,000 ebooks in its collection. If you can find one to use instead of requiring our students to make a purchase, we can collectively save our students lots of money. What are desirable characteristics of a book to be included in a course?
DRM is "Digital Rights Management. DRM enforces rules like
Your best option is to use an ebook from a collection that is DRM-free.
Some ebooks only allow one user at a time to use them. What happens the night before an exam if all of your class wants to use the book? They are blocked out. The best options is to use a book with unlimited number of users.
Some ebooks are leased through a subscription. If a publisher changes terms or editions, a leased ebook may "disappear" from the college collection. Other ebooks are purchased. We will always have access to purchased titles. The best option is to use a book with perpetual access.
Sometimes you may have to compromise on one or more of these three important criteria. The best choice is to consider all three options and make a balanced decision in your students' best interest.