EULA - End User License Agreement
The License or Webix attribution CANT be removed from source files
The provided code CAN be modified in any way that doesn't conflict with the above statement
Webix library CAN be used in any private project which wont be shared or sold
Webix library CAN be used in publiс projects. BUT in that case you MUST share the full source code of your project.
Webix products under Commerical License can be used in non-GPL projects and don't require sharing full source code of the project.
The rest info about Commercial License Agreement you can find here: http://webix.com/licenses/developer-license-agreement