Commercial plugins seaminglessly integrated?

Hi,

I am interested to create several commercial – but GPL – plugins. I read that they are seaminglessly integrated but as it look, the people can immediately download each plugin and there is no hint in the list that a plugin is commercial. There is a difference between downloading the sources (without assets like images and css) or downloading the whole installable and runnable package, so I am a little stuck here.

So my question to the community is, how is it done right for developers to publish commercial plugins and not to get into conflict with existing rules?

Regards,
Markus