SlackBuildsOrg/network/nordvpn

The NordVPN app for Linux protects your sensitive data with military-grade
encryption, so that whatever you do online stays secure and private.
More than 5000 servers worldwide. No logs of your online activity.
Secure up to 6 devices with a single account.
Access online content securely, with no restrictions.

The following can be used to start/stop NordVPN automatically:
/etc/rc.d/rc.local
  if [ -x /etc/rc.d/rc.nordvpn ]; then
    /etc/rc.d/rc.nordvpn start
  fi

/etc/rc.d/rc.local_shutdown
  if [ -x /etc/rc.d/rc.nordvpn ]; then
    /etc/rc.d/rc.nordvpn stop
  fi