I decided to research the advantages and disadvantages of owning and borrowing Kindle books. I am interested because I publish a Kindle book and also because I purchase an average of about one Kindle book a month.
As a reader
Amazon Prime $100 a year provides the opportunity to “borrow” one book from the Lending Library per month. Amazon claims there are 500,000 in the lending library. Not all books are available, but this is a pretty good collection. You do need to own an Amazon Kindle device and not just the app to take advantage of this opportunity.
Kindle Unlimited costs $10 per month. You can keep up to 10 books as long as you continue to pay the monthly fee.
I am guessing these three alternatives – purchasing approximately a dozen books a year, borrowing a book a month with Prime, or the Kindle unlimited plan would work out about the same for me. Presently, I have the books I have purchased. I seldom return to these books, but I could. It appears you can save your highlights and notes in all cases. However, when you own the book you can go back from the saved highlight or note to the page in the book should you need additional information. With Kindle Unlimited, you could take a look at more books and focus you reading time on what you found to be most useful.
The best plan for you could also depend on other factors. With Prime, you get free shipping and you could think of access to one book a month as a freebie.
While the unlimited plan seems attractive, I would say you need to be a heavy reader to make it the best choice.
As an author
What about the situation for the author? When someone buys your book, you receive 70% of the cover price minus a small amount for sending the reader the book online. This means I receive about $6.25 for a book sold in the U.S. When someone reads our book as part of a borrowing or unlimited program, we receive approximately 5 cents a page. I must admit that I read this online and the amount seems close. The report I get from Amazon is not clear. Amazon appears to set aside an amount of money and then divide it up based on the number of pages served through these various programs. I am also not certain exactly how the number of pages in a book is determined, but Amazon lists our book at 99 pages. This means we receive about $5 if someone reads the entire book through one of these lending programs, but does not keep the content.