Ebook Central license upgrade pricing relates to historical spend
When upgrading to an unlimited license, it should be taken into account when the institution has previously paid for multiple 1 or 3 user licenses.
In these cases the institution should be invoiced for the difference between the total spend to date on licenses for that title, rather than the current model of the difference between the unlimited user license and the cost of a single 1 or 3 user license.
Nathaniel Pockras commented
This would be appreciated. Some time ago we firm ordered docid=4091378 with 1U, and later upgraded it to 3U because of turnaways. We later bought another 1U copy (not sure why; maybe a mistake?), and when the book kept getting turnaways, we had to pay the price of upgrading the 1U copy, not the price of upgrading the 3U copy.
I wonder if this would be a problem for publishers, however — let's say you buy two 1U copies for a book that's not sold with another license. Some time later, the publisher starts selling it with 3U, and the price is less than twice that of 1U. Suddenly you can upgrade from 1 copy to 4 for free, even though they didn't cut the price. Nice for library, not nice for publisher.