Plugins sold by CodeRevolution are not 100% GPL, but are under the ‘Split License‘.

The Split License means that when you have multiple code types and assets within a composite item, some elements will be licensed for others to use on a ‘proprietary’ basis (that is, placing restrictions around the use of those assets) whereas anything that needs to be licensed as GPL will have the relevant GPL version apply.

As an example: parts of plugins like CSS, design, photos, graphics are usually subject to the restrictions of the ‘Envato part’ of the split license (for example, only one End Use is permitted) but the PHP and integrated HTML fall under the GPL, which means buyers are free to use and distribute the PHP and integrated HTML, as long as they do so under the GPL.