According to the page of the DMCA you should have a certificate or badge, although depending on the type of copyright that you have added to your plugin I suppose you can always do something.

There he explains the steps to follow, I am sorry if the translation is not of the all right .

Reports copyright infringement

Please follow these instructions when reporting stolen content:

www.theiveswebsite.com/stolen_content/stolen_title?chptr_12234.aspx

Useful links ( in English ):

• CONTACT
• FAQ

Prevent us from being hacked:

First of all, to say that I am a supporter of the Free and Open Code, but licenses are essential, and I do not only talk about payment licenses, since I do not know much about those, but whatever you do ( Put yourself ...), seriously, give her a license. Neither you put a BeerWare or a GNU GPL ...

but

always give your code copyright / license

With copyright / license you will have your protected code in case something happens, now, my recommendation, apart from this, is that you put a kind of AUTH_KEY to your plugin, to avoid hacking.

You simply need a server / webservice / microservice or something that you can put online to perform an authentication similar to that performed by wordpress theme developers or the google maps API.

Any page that uses your code should make a small request to your server to check (at least):

• domain
• auth_key
• (license number?)

That request will come from the domain where your plugin is being used and will be of the style:

http://www.dominiocliente.com/nombrePluguin?auth=HXCADOUFUEHFDLAKJVCNBEBE

If the license exists , corresponds and is in force , the request returns an ok, (it is usually a cookie to avoid queries every second, but even if it's a OK it will be fine).

Otherwise, you are denied access and thus the operation of the plugin.