If third party is accessing the payable book get the licences from the publisher to paste the code in your website and make visible to all from your website. Here image shows how the book is present in you website from Google books.
The same option provided in embedded code to read the book from the particular page. If the particular page is to be displayed in your website from Google books , go to the page in the book (example here..) which you want to display it in your website copy the embedded code on this page , so that the same page is made published in your website (same page will be opening page of the book).
This option plays a role in a quite simpler manner to neglect unwanted page form the book such as adds, author bio and index these pages can be neglected by choosing the exact page to be displayed first example here . The embedded page will be in image form – so no copy text can be done.
Note : Get the authorisation form the author to use the book in your website