SuperMemo itself is free, but components making it usable are non-free.
From website:
Additional features
multiple user management; with only one installation many users can learn from the courses, without the need to copy them,
simultaneous learning from many courses, without the need to switch between them manually,
selection of the material, including and excluding it from repetitions,
a built-in keyboard with diacritics of a given language,
a concise dictionary including the course vocabulary,
a schedule of the repetitions planned for a given month,
automatic online update of the application and course material,
a built-in speech analyser, which allows you to test and correct your pronunciation on your own.
Old test results
The test results for this version are very old, and as such they may not represent the current state of Wine. Please consider submitting a new test report.
Selected Test Results (selected in 'Test Results' table below)
What works
Installing, creating user, adding new course, most of exercises.
What does not
Troubles with graphics, updating beyond some point, problems with fullscreen (after start push F11 to set window mode), sound only in flash player mode.