If you get a 407 error when trying to activate an Extradium license key, please try to configure the web.config of your Central Administration web application by adding the following entry inside the <configuration> element:
<system.net> <defaultProxy useDefaultCredentials="true"> <proxy usesystemdefault="False" proxyaddress="http://[proxy address]:8080" bypassonlocal="True" /> </defaultProxy> </system.net>
You can also try to temporarily disable the proxy filter for your Central Administration server's IP address, if your proxy server allows such a configuration.