First, thanks for your purchase.
You needn't to activate the revolution slider on your end.
We are also using the revolution slider without activation. https://prnt.sc/uc0i0w
The activation key is only worked on one domain website.
If this plugin is updated, we'll add the new version in our updated theme version.
So, you needn't activate this plugin.
If you have any other questions, please contact us again without hesitation.
Best Regards, C-Themes