It's impossible to say when the product will be compatible with Windows 10, because the current version even lacks support for Windows 8/8.1, which is a major issue. However, there are emails posted on the Contact page where you can send an inquiry to the developers to ask about Windows 10 upgrade for their applications. This way you will get an official response about the release or upgrade to Windows 10.
Contact page: http://support.ebooksys.com/contacthome.php