How can I tell the difference in a Serialized and NUL Acrobat DC, from the registry?

We have mostly NUL installations but there are still some serialized in the Enterprise. We are trying to track down a way to separate the two by using the registry, but we have been unable to locate a reliable difference. I know we could just remove the serialization from everything but that's not currently an option for some PCs that we aren't ready to convert yet.

I can't find anything anywhere, registry or otherwise, that let's me tell the difference in the installs.

Anyone?