This error normally occurs when there have been too many failed license registration attempts (wrong license key) and your IP has been temporarily blocked by our firewall for 24 hours. This is a security measure to prevent brute force attacks.
Wait for at least 24h, verify your license key and try again.
If you still can't register the license, do not keep trying or you will be banned again after 3 failed attempts. Instead, verify your license key - there probably is a typo (wrong number, spaces, ...) in the entered key. If the license key has been provided to you by a reseller, please contact them to double check the key.
If you copied and pasted the license key, it is also possible that some invisible caracters, such as spaces, have been accidently pasted.