Hi Timm,
You can familiarize yourself with cineware integrations on our documentation webpage Maxon Cineware User Guides. Specifically for the After Effects integration there's a compact but rather informative description (as well as pointers to a corresponding video footages at Maxon's Youtube channel) on a dedicated webpage Cineware for After Effects:
Adobe After Effects includes a free installation of Cinema 4D Lite – a limited but feature rich version of Maxon’s award-winning 3D software package. Cinema 4D Lite can be accessed directly from within After Effects in the File ⇒ New menu, or by clicking Edit Footage on a Cinema 4D layer in your composition.
The question about proper licensing behavior of your plugin lies outside of scope of knowledge and highly depends on the goals you're trying to achieve. As I already pointed out, say, the scene with some object defined in the external plugin would require this plugin to be loaded by cineware as well to function the same way as in C4D.
Cineware integrations use preferences folder different from the one that is used by Cinema 4D (it uses the same folder name with suffix _w). Hence, all the preferences (including the world container) are not shared between C4D and Cineware. The behavior of some function call can also differ, including GetGeneralLicensingInformation(). However, the system identifier systemId is independent of the APPLICATIONID and will be the same in both cases.
Let me know if you have any further questions.
Cheers,
Ilia