Each site has an individual licence for Bildy editor. Everything loaded from Aisti's servers is owned and copyrighted by Aisti. In normal plan, you may have as many people developing or updating one site with Bildy editor as you wish. If you're using the mini-plan, you can have one developer and one updater managing the site. Personal plans are limited to one developer.
All the material that is located in your server space is owned by you (or your customer). You may modify, distribute, publish or sell that in anyway you want. What this means, is that you can also the Bildy engine or controls of your site. All the program code in Bildy engine is OSL licensed. Bildy controls created by Aisti are under MIT license and you can create your own controls using any license you wish.