Plugin will not register in Network Install | CyberSEO Pro | Support Forum

Yes, that's correct. If you haven't bought an unlimited license, you have a limited number of installs. I mean a one-site license can be used at one site only. A 5-site license can be activated at 5 sites etc.

Your subdomains are different sites. The CyberSEO Pro license is being issued for a site. Not for a domain, hosting, or even a subfolder. It's like if you buy a Windows license, you should assume that it will work at one computer only. It won't work at all computers in the same room, house or city. You even can't transfer it from one PC to another. If you want to run at all computers in your company, you but a corporate license. The same rule works with CyberSEO.

Please check the "Limitations" section in the TOS: Login to see this link

In this case the credentials you enter are wrong. I've just checked your license. It was issued on January 3, 2020. It's really unlimited and it's active. Please email me with the name/email you enter to activate the plugin. As you understand, we can't discuss your personal info on the public forum.

The credentials were incorrect. Perhaps you have prolonged your license using a shortened name. Note my email.

P.S. When you upgrade/prolong your license, always use the same name as you used when you was buying it for the first time.