Domain name change

We’re changing domain names, so naturally need to transfer the licenses. I have deactivated the plugin on the first site, deleted the site from Security Monitor and Connected Sites. Still not able add the new site. We have a license for 10 domains, I see 8 sites connected after deleting a couple of subdomains. I will need to do the same for more subdomains as well. I get the following error when trying to activate the license on a new site:

ERROR! Your already activated your account for a different website.