After effects Lighting Problem

Given the limits at Rick and Mylenium have explained, could you take a duplicate of your element layer, replace the textures matte grey and then render out with only 8 lights turned on, then repeat for the remaining lights and then combine these renderings onto your original using transfer modes.  Sort of a low budget lighting pass?

Alternatively (and I say this as a big fan of Element compared to C4D Lite) could you recreate your animation in C4D Lite with the additional lights?

In addition to what Rick already said and as a slight correction to it this isn't even an arbitrary limit in E3D, it's a hard set limit in legacy OpenGL such as used in the plug-in when not using the advanced shading and GL raytracing.

Mylenium

Click on Help Center in Scene setup and check out the Manual. That is a built-in limit.

If we knew exactly what you were trying to do there may be another solution.