Thanks for asking.
You can't use X Theme licence to Validate Visual Composer, it won't work and you will have to buy a separate licence from plugin author. More importantly there is no need to activate Visual Composer as it's a bundled plugin that comes with X Theme. We will provide all the updates for Visual Composer upon testing there compatibility with our products once updates are released by the plugin author, wpbakery.
Please take a look at our product validation guide for more information.