Google has carefully considered copyright laws and has prepared free books that are available to read for everyone. Some books are not protected under the law at all, e.g. US government documents are not protected under the law.
Google Play Books offers no subscription service, so you must pay for individual titles at the price that they retail for. There is no money back guarantee if you buy the book - you are only buying the book.
Jane Austen's Pride and Prejudice, The Souls of Black People by W.E.B. DuBois, The Count of Monte Cristo by Alexandre Dumas, and many other books by English poet Phillis Wheatley are all available for free on Google Books.