All our e-books is delivered with the following Licence Type.
Downloadable License Type: Perpetual Licence
If you download the e-book in Bookshelf to a mobile device, Mac or PC your e-book will always be available on that unit unless you delete Bookshelf.
Online Licence Type: 365 days
The e-book is available for Download during one year from delivery. You also have access to the e-book online at https://bookshelf.vitalsource.com/ for 365 days.