No, DRM usually doesn't involve plugins phoning home. It's done once when the plugin is loaded, and that's it. As for editing the plugin, that's up to the license provided by the author. Paid plugins typically don't allow modification, even for personal use, to minimize the support overlap. But yes, this would prevent you from editing plugins. You'll want to communicate with the author to implement changes instead, which is why you should do either way, IMO.