You will not be able to update the Visual Composer Plugin since you need to have license key. We could not give you the license key because it is against the terms and conditions of Codecanyon.
The premium plugins are included under extended license article : https://codecanyon.net/licenses/terms/extended , which allows WPLMS to include them in the theme. The plugin authors however can sell the support for their plugins saperately and ask you to purchase the license but it is not “required”, you can simply skip or dismiss their notification asking you to purchase the plugin license.
How to update Visual Composer :
Method 1
1. Update the WPLMS Theme
2. Login via FTP of your server , locate the WP content/plugins/js_composer folder
3. Delete this folder
4. Login to WP Admin and you’ll see a notification that visual composer is deactivated.
5. Go to WP Admin -> Appearance -> Install plugins
6. You should see Visual composer, click on install and activate the plugin.
Method 2
0. Make sure theme is updated to latest version
1. Go to WP Admin -> Plugins -> Visual composer
2. Deactivate the plugin and delete the plugin.
3. Go to WP ADmin -> Appearance -> Install plugins and install and activate the visual composer.
Method 3
1. Go to WP Admin – Plugins and deactivate and delete the Visual composer plugin.
2. Download the latest version of WPLMS theme from themeforest.
3. Unzip the package
4. Locate the theme file and upzip it.
5. Locate the wplms/plugins folder and locate the js_composer.zip
6. Go to WP Admin – plugins – add new and upload the above file.
7. Latest Visual composer is now installed.
NOTE: Visual composer in WPLMS can only be updated with the theme updates. It may happen that the theme has outdated version of VC if there is a VC update in between theme updates.
Refer Video :