In this case, please go to the ‘Activity and Logging’ section of the plugin. You will see an error message that starts with:

Failed to get verification response: …

Example:

Failed to get verification response: Failed to connect to coderevolution.ro port 443: Connection refused

The above message means your hosting provider is blocking access to my registration server by a firewall rule. Please contact your hosting provider’s support, and ask them to allow connections to coderevolution.ro from your server.

Also, each error message that appears in the above error, should be communicated to the hosting provider’s support, and they should be able to fix it.