This library management tool would be worth your while for ebooks:
http://calibre-ebook.com/about
Together with plugins from Apprentice Alf you can strip copy protection from the ebooks you buy and format shift them as needed. Recently the .Lit standard (once the largest market sector) was abandoned so it behooves you to format shift whatever books are important to you as the years progress.
Thanks, I have Calibre on my Linux pc, didn’t know it was avail. for Android. Now I do.