This plugin cannot qualify as GPL compatible. The code is obfuscated with the ionCube encoder.
The only plain php file is the minimal one required to contain the plugin header, 'memberwing_head100_free.php' and the ionCube loader itself.
The plugin does not indicate any licence at all.
The License for the loader is definitely not GPL compatible.
1.1 The Loader is provided free. Title to the Loader does not pass to the user in any circumstances. The Loader is supplied in object code.
I believe this plugin should be removed from the repository