Freemyip.com is a free dynamic DNS service that does not need either any registration nor user account to maintain dynamic DNS based sub domain name such as example.freemyip.com. The validation of the domain ownership is based on an access token that should be kept safe in order to update the sub domain with your computer’s public IP.
I have written a simple Python3 script that allows the sub domains owner, to update the IP easily, with keeping in mind avoiding flood access to the service itself by logging the latest updates and preventing access if the IP is kept fixed for specific period of time.
The script could be found on freemyip-python repository on GitHub. The script is very simple and the README there is probably enough to show the script usage.