When I was a self-published author, I did a lot of background research on all things marketing, revenues' avenues, etc. I have said that before: unless you write purely for kicks, self-publishing must be treated as you would any other jobs. You work, you get paid. A customer uses your services, you get paid. Often, though, authors are not always aware of all the revenues' avenues available to them and risk losing out.
One such revenue stream is what we call PLR, or Public Lending Right. Essentially every time someone takes a book out of the public library, a small amount of money is allocated to the author/editor/artist, etc. The Rate Per Loan for this year's (2017) UK PLR payments is 07.82 pence. It's not mind-boggling, but every little helps, as they say. More details can be found on their website.
Since my first book came out in 2012, I have registered all my books, and all editions of the same book, with the PLR scheme, and every year, in February, I regularly receive a compensation proportionate to how many times my books have been taken out on loan.
Now that I am a publisher, I cannot claim money for the books we publish, of course, but our authors can do so. The percentage of how much money you are due is also dependant on your role in the book. For example, an editor of an anthology will be able to claim 20% of the allocated amount, while the authors of the stories will share the remaining 80%; if you are the sole author, you can claim 100%, and so forth.
The first thing you need to do is to register. Now, the following apply to UK and Irish authors, but your country will have a similar scheme (hopefully!)
Visit https://www.plr.uk.com and apply for an online account. You will be asked for payment details, as the money will be sent to you through it. Every time you release a new title, you add it to your list - the online instructions will guide you through this process quickly. They then review your request, message you if they need to clarify any point until the title is added to your 'approved registrations' list.
The statement arrives in January, and it covers the period 1 July of a year to the 30 June of the following year. Keep this in mind when you register a book.
This year they have also approved the inclusion of the remote lending of ebooks. Don't forget to register those too!
Public Libraries have come under a lot of pressure, with spending cuts a go-go. They will acquire titles from specific distributors and wholesalers, but it is also possible that they will consider gladly accepting a donation of a free copy or two. Whether you are self-pub or are published by a company, keep this in mind, as authors' own self-promotion is very helpful.
So, if you have books roaming the world, but you have not yet registered with PLR, DO SO NOW! It's your money after all.