You will need to have a local library account, which may require you to visit the library at least once to obtain the account. (hubpages.com)
Currently it only supports one library account at a time, but some folks at MobileRead found a workaround by signing out of your library and signing into another one. (blog.the-ebook-reader.com)
We account for about 10 percent of publisher sales5 and 40 percent of children's.6 Public libraries account for about $ 1.8 billion of sales a year. (publiclibrariesonline.org)