If you're having trouble requesting a license having launched VNS3:vpn (Formerly VNS3 Free Edition) then check that your VNS3 instance (we call the "Controllers") is able to reach our license server - it must having working DNS so that it can resolve our license server's public DNS name to an IP and have outbound Internet connectivity (at least access to DNS and TCP port 8081 for speaking to our license manager).
We allow two VNS3:vpn Licenses to be registered per customer. VNS3:vpn licenses are tied/associated with the underlying instance/VM that was used to make the request. In the event you made a mistake during configuration and terminated the VNS3 instance/VM and need a new license, open a support ticket and our team will clear out the errant and unused licenses.
Next time you want to clear your configuration settings and start over without the need for launching a new instance and requesting a new license, use the "Reset Factory Defaults" feature.