Replacing the license key on your Artifactory instance can be done by one of the following:
Go to the Admin→ Configuration→ Register License → replace the license key. This method does not require a restart of the Artifactory instance.
Go to the $ARTIFACTORY_HOME/etc/ folder, → edit the artifactory.lic file→ replace the key inside the file to the new one. Please note that this will require a restart of the Artifactory instance in order for the new key to load.