Ebook Central is a big subscription package, though we do have the ability to purchase licenses for individual titles. This means that most of the books in here are part of one big package (as opposed to individually selected by the LSC librarians), and that books will leave the collection sometimes when their license is up.
When you click into a book record in Ebook Central, an "Availability" statement is shown before the summary. Because nearly all these books are part of the subscription package, you can expect to see a statement of unlimited user access.
Below that will be lines letting you know how many pages of the book you can download as pdf and print.