After you have registered your email address you will obtain a token. Then keep sending this token back, as HTTP POST request parameters. Once your IP address changes this site will notice and notify you via email message.
Here is en example using token "0123456789".
You can send such request using
Now you have chosen way of sending single request, configure your OS to do this request every few hours. Simplest way would be "Windows Scheduler" in Windows and "crontab" for unix based OS.