The number of pages that can be printed is regulated by the publisher and complies with copyright law. When printing, you'll receive a message saying how many total pages are allowed to be printed and how many you have already printed from the book. (from Williams College Library)
Printing from Ebook Central is restricted to approximately 20% of the total pages of the e-book, per user. Copying and pasting content is restricted to approximately 5% of the total pages of the e-book, per user. Ebook Central will display a message if the limit is reached. (from U Texas Libraries)
After 10 minutes of reading/browsing you will be prompted to check out the book. If you want to check it out, click YES to "checkout" the book. You will need to download and create an account with Adobe Digital Editions.