My current Vuescan license is from 1999. And I think that one was just to replace an older serial due to some upgrade on their end. It's probably the most bang for the buck of any software I've actually purchased.
I don't do much scanning anymore, but I do have an ancient Nikon CoolScan 35mm scanner that's probably at least 20 years old now. I get it out every few years to scan something I found and, with Vuescan, it still works remarkably well.
Although the last time I fetched it out from a storage container by our barn (I really should store it in the house) I found the negative strip scanner wasn't working anymore, but the slide adapter did and that was good enough for the task at hand.