You will need to have installed and running the No-IP DUC (Dynamic Update Client) program on your
desktop (not laptop) to keep your account from expiring. The No-IP DUC program will "tickle" no-ip.com on a regular basis to let them know the service is still "wanted" and running. Make sure this program is running on the desktop at all times.
You can download No-IP DUC from the official website
here.