Publisher provides electronic access at no additional charge if the library subscribes to the print version. Libraries are expected to continue the print subscriptions. This is the approach suggested by Elsevier. Publisher limits access to specific building locations. For example, the American Society of Microbiology license specifies that access would be limited to the Briscoe Library.
Publisher sets prices by number of simultaneous users.
Ovid Technologies Inc. is an aggregator as their Biomedical Collections I - IV are comprised of journals from various publishers. Libraries can license specific numbers of simultaneous users to the journals in the Collections. Because we are currently in a transition period, there is a lot of experimentation. Electronic resources are adding to the complexity of managing libraries. They are also changing patterns of use.