[Gelöst] Unable to register: Site key not matching

Background of the issue:
I am trying to register the site key for WPML. Additionally, I am using an unregistered version of WPML, which means I cannot receive compatibility and security updates. The issue can be seen at versteckter Link

Symptoms:
Unable to register: Site key not matching

Questions:
What should we do to register the site key?
How can we resolve the issue of using an unregistered version of WPML?