Include Max mega menu Plugin into theme

If you include a plugin directly inside a theme then it will be rejected by both the WordPress.org theme directory and ThemeForest.

You should use TGMPA for including plugins with themes: http://tgmpluginactivation.com/

Further reading: http://code.tutsplus.com/tutorials/using-the-tgm-plugin-activation-library-in-your-themes–cms-20901

Using TGMPA means the plugin remains a plugin, WordPress loads it in the normal ‘plugin’ way, and users will get plugin updates as they’re released.