An agency asked me to look after a Wordpress website as the customer wasn't happy with the current developer. I got the admin login of the website, logged in and was suprised to see an older version of the BeTheme (12.9). Yet the theme and the child theme are named differently. After seeing the theme options and the muffin builder I checked the source and sure enough, it's the BeTheme. Besides changing the themes name the menu "BeTheme" ("Install Plugins" etc) has been removed. The theme options can only be accessed through the "Design"->"Themes" module.
The whole situation is dumb, as the customer can't update the theme or the plugins such as the slider revolution.
My question is: Is this allowed or is someone selling your work as his?