Not sure what version your are using if you need an unlock key to install the BB KVB apk. Any of the versions I have ever installed on Android never needed an unlock key.
Originally, I think it was only available to get via cobalt's manager, unless one had an actual BlackBerry Android Slab. However, later I think all the "patched" apks Cobalt was providing via his "manager app" were also directly available on his file site. I don't remember any of them requiring an unlock key to install. Maybe a password to get into his file site repository, after he was told to cease and desist. However, by then I don't think he really was patching the apks anymore because by then I think BlackBerry had the suite (except the keyboard) available from PlayStore.
If one searches hard through CB, one can still find a few rogue sites I think from where to get the last version of the BlackBerry VKB apk. It used to be easier to find from the CB threads and posts, but sometimes it's hard to find certain posts in there nowadays.