Audible is an Amazon online e-book store. It offers the first book for free! The monthly membership fee is $14.95. It has all genres, is available in foreign languages, and has a gift center. Preordering is also an option.
Even if you cancel the membership, your books stay.
Audio Books Corner is an online audiobook store that is available worldwide. It also offers some free downloads. There is no monthly subscription. No extra softwares needed for playing their audiobooks.