That's limited to 4 vehicles per computer install of the software...so if you have a laptop & desktop PC, you could actually store 8 vehicles worth. You can also remove a vehicle and add another in if you need to. Just make sure you have all the IDs when you do that or you'll be a little stuck. I've got a text file saved on my computer that lists the OEM IDs and my Winter IDs. When I swap the tires, I make the quick update.
I can understand your thought process behind this. I know for me, that I'm less likely to keep an eye on the pressure during winter so I'd rather have the ability to update the TPMS IDs when I swap the tires. The light drives me nuts on the dash, too. While I don't consider them necessary, per se, I think they offer a benefit to the less mechanically inclined and to those of us that may slack a little in bad weather. I do wish I'd known about the set for $52, and maybe I'll go back and bookmark or add the seller to my favorites for a future reference. I know, there's no guarantee they'll still be an ebay seller if/when I need them again, but since it's an easy thing to plan for I'll add them anyway.