huh.. Weird. I had Google Play Services completely disabled as I try to only have background services I actually *use* running in the background. I don't use location services whatsoever (Maps, contacts, backups/cloud storage, etc.) I do everything manually.
But yes. In Google Play Store, when it was disabled, I only had the option to "Buy" the Pro Unlocker from the Play Store whereas after I had re-enabled google Play Services, there was an option to "Install" it. That seems to have fixed my issue. And it does appear I'm able to use it on multiple devices, currently running on 4 for anyone wondering for future reference.
Kudos for the quick reply nonetheless.
-D