Ask HN: How do you keep track of software you've delivered to clients?

I'm looking for good ways to keep track of which software (and versions) I've installed on my customers' infrastructure. The purpose of which is to know which customers I need to visit after a vulnerability has been found in a piece of software I've installed there.

Right now I'm using a simple spreadsheet, but I'm wondering if maybe there's something better out there? Something more tailer to the task?