OK, I started messing around with the Zebra demo, and forgot all about this thread...
Anyway, I did download and install the latest version, and it appears in Live 9 (64-bit)'s VST section, and I can drop it on a MIDI track (which opens it in demo mode) but it doesn't make any sound. Pressing keys on my MIDI keyboard does not do anything (it doesn't even move the virtual keys in Sylenth1) and clicking the virtual keys with my mouse does not produce any sound.
I used download link and password I got from Lennar Digital when I first bought Sylenth1, but it seems like it's still the demo version.
post on the KVR forum if you have an account, or email Lennard/support directly.. gotta either make noise or bug him about fixes.
there's been a lot of issues regarding Windows 8 and the 'demo voice' popping up even after being registered. i've been looking at upgrading one of my computers to windows 8 but have held off as it doesn't seem clear whether this bug is actually fixed, or in part user error due to administrative rights, etc..
there's been a 'pre-release' fix apparently available from the email you originally got your download links from.. but since I do not run windows 8 currently - Lennard suggests I do not need the fix, and need not worry about asking when this 3+ month old 'pre-release' will turn into an actual release and inform customers of a fix.. (currently the only way to know about this fix is from the KVR forum, or maybe if you email support with the same bug)