Can we buy licenses for e-books and lend them to students? We are thinking about buying new textbooks for our students. Is there an established practice of buying digital copies of books for students? I expect that e-books should generally be cheaper and we might also be able to save money on delivery.

If the school were to purchase 10 copies of some particular title (e.g., this condensed matter physics book), would it be possible to loan these e-books to one set of students for some period of time (2 years), and later use the same licensed e-books for the next set of students?

Edit

I'm asking is it legal to give the same e-book file to multiple student generations, given that the particular licensed copy is only used by one student at a time.

If it is legal, I'm interesting in the established procedure for doing so. Are there any special considerations for different vendors or for different e-book formats?
Generally speaking, when you purchase digital content, you are usually purchasing a license for said content. You will have to read the license to find out what the terms are. For example, here is the general license agreement for the Kindle store. It states that as a general rule:


  Unless specifically indicated otherwise, you may not sell, rent, lease, distribute, broadcast, sublicense, or otherwise assign any rights to the Kindle Content or any portion of it to any third party


which would prohibit the scheme you suggest in the general case ("unless specifically indicated otherwise").

Similarly, for books sold in the Google Play store, the license terms include the following:


  You may not lend or co-own any of your Books on Google Play purchases with another person.


The specific license terms can vary by content distributor, publisher, and individual book. 

In cases where lending is permitted (e.g. some Kindle books), it's usually very restricted - for ordinary customers. Libraries can purchase licenses for some books that are more permissive for lending purposes. You should consult with your university librarians about what options are available to them.

You may be able to find an appropriate book for your purposes with a permissive license that allows lending (maybe even some open educational resources, if you're really lucky), but this will probably take some work.