Hello Carl,
Thank you for your message.
Do you mean the Host's certificate that can be found in the
Host Settings -> Host identity tab? If this is the case, then please note that it's used for an automatic certificate-based Host identity check mechanism.
Host's
Internet-ID code is used when you want to connect to a remote Host using Internet-ID connection. For more information please see
this page on Internet-ID connection.
As for the license key - it controls the limit on how many remote connections you can add to your address book, for example, free license allows to add up to 10 remote Hosts. For more information on the license types please see
this page.
Hope that helps.