About 5 years and 3 employers ago, I was working at a government agency building an admin console for a home grown messaging system. This messaging system, which was around 30-years-old, was built for purpose and pretty reliable. But it suffered an outage one day, and when I leaving, there were plans to replace it with something off-the-shelf from an outside vendor.
Yesterday, I got a message from a contact that is doing some consultancy work there. Apparently the home grown messaging-system system was still going strong, and the admin console I built was still being used.
I guess software really does live for ever.