Always have a backup licensing machine, or better still a VM
The piece of server software that covered the majority of sales when I started work was OS/2 based, and towards the end of its life licences were issued by one OS/2 machine in the US. It became increasingly difficult to get licences as the machine obviously wasn't well maintained or documented, and the supplier hadn't bothered to port the licensing software to Windows complete with OS/2 support, when the server software moved to NT.
Poor show, especially considering it was per seat licensing, each one was not cheap, and there was a healthy reseller margin included. For receiving a fair bit of money for not doing very much, the process really should be as streamlined as possible.