Different vendors offer different access models for their e-book content. Currently there are two major access models, with variations therein.

1. The library purchases the content and owns it in perpetuity. Each year, the library’s allocated e-books funds go toward paying for additional content. Some vendors require that the library pay an additional annual fee to “rent” the platform through which the content is accessible.

2. The library subscribes to the content and pays an annual fee to provide access to it. This is the model most familiar to libraries with online content, as it is how most subscription databases are purchased. Usually, the vendor guarantees to add a specific amount of new content per year, and the library pays its flat subscription rate to access all of the content contained in the collection.