I recently purchased the Zorin OS 16 pro version but in the installation process it never asked me for the key and now it's showing I have basic Zorin OS 16 installed.
Can someone please help me with letting me know how to activate my copy of OS?
There are no DRM and or activation processes on Zorin 16 Pro. There are no issues here
Zorin 16 Pro is a way to support the developers and the Zorin team did not include any DRM measures in their product.
In order to install Zorin 16 Pro, download the .ISO file that has been emailed to you and use that to install Z16 Pro.
I did a quick check in the settings menu and there does not seem to be an option that reflects this.
A dirty way to do it would be to see if the Wallpapers/Apps seen on the Z16 Pro page are available on your device.
Also Z16 Core takes roughly 9.5GB of space while Z16 Pro takes about 25 GB.