i bought PopUp Pro for ecartec.com. Now the customer want

Hi,
i bought PopUp Pro for ecartec.com.
Now the customer want to have your plugin at marterialica.de also.
We have cloned the site ecartec.com to materialica.de (with all Plugins).
So the question is: do i need to buy your plugin once again. or will your plugin run on materialica.de also?
or do i need anonther API Key?
Thanks,
Felix