Visual Composer and WPBakery do not offer multisite or developers license at the moment. In terms of licensing we fully rely on Envato standards and at the moment there are two licenses available:
- Regular/Single use license
- Extended license
None of these two allow usage of Visual Composer on several sites independently. In case you want to use Visual Composer on several sites be sure to purchase one Regular license per each site. Read more aboutl icensing.