The7 is one of popular premium themes like Avada, X, Enfold and BeTheme. This theme supports IE 10 or higher and is also compatible with WPML, WooCommerce and bbPress. Please refer to the theme site for more information.
The copyright information or credits can be modified under the theme option "Branding." (The user manual of The7 is found at this site.)
Likewise, most paid-in themes provide users with an option to change the copyright information easily.
For example, you can change the copyright credits in the Footer > Copyright section of the Theme Options in Enfold.
If such options are not available, you might need to edit the theme source files manually. In general, the file to edit will be footer.php depending on themes. You know, it's desirable to create a child theme before you make any changes to your current theme.