If you have purchased a license like facial recognition, people counting, or cloud archiving, then applying those licenses to specific cameras is simple.
First, go into Settings->Licenses. In there you should see all of the licenses you have purchased. If any are missing, please reach out to your sales contact or support to resolve that issue.
From there, you can choose any license and choose "Assign" to pick a particular camera to attach it to. Once the license has been assigned, it takes just a few minutes for the camera to be configured with that license. You can "Unassign" a license in the same way if you want to transfer that functionality to another camera.
Please keep in mind that if you Unassign a Cloud Archiving license, then all stored footage for that camera will be lost.