Leanpub never owns the copyright on anything published on Leanpub.
The copyright to your book or course is entirely owned by you, the author--unless you are writing the book for a publisher (such as an institution). In that case, the publisher can choose who owns the copyright.
For an individual author writing a book, you can choose either the default copyright or a customizable Creative Commons copyright. This is done at:
...making sure to replace YOUR_BOOK with your book's unique web address.
You can also customize the attribution and dates of the copyright, which will give you the following options:
Custom Copyright Owner
If you don’t put anything here, the book will be copyright by your name. Only fill this in if you need to override this with something else, like your company name or a list of people.
Copyright Custom Date Range
If you don’t put anything here, the book will be copyright from the year you created it on Leanpub to the year you last publish it in. (If these years are the same, that year will only be printed once.) Only fill this in if you need to override this with something else, say if you are including old material and you want those years included too. An example format of the text you enter here is “2007 - 2012”.