[EstateEngine] Using the required plugins: Visual Composer and Revolution Slider
After you install your theme, you’ll see a notification appear on the top of the site. It reminds you to update the supported plugin Visual composer.
You can learn more about the plugins following these links:
Also, please note that you don't need the license key to get the plugins' updates. Since the plugins have been already integrated right in your theme, you can visit your member area and get the new releases and update via your FTP.