Contra some of the suggestions, I would NOT re-use that spare as a daily driver for two reasons:
1. At five years old, it may have degraded somewhat, as already noted. In fact, if it's mounted underneath the vehicle (typical for many trucks, vans, and utility vehicles) then it almost certainly has, due to salt and elemental exposure. If mounted on the tailgate without a cover, then UV exposure has taken a toll.
2. It likely has a different tread pattern then whatever you buy to replace the others. This is usually not fatal if the tread application is the same (e.g. all-seaon light truck) but could have odd effects on grip and handling, particularly during emergency maneuvers and off-road duty.
I've had three cars with full-sized spares, but have never rotated the spare into the succession. I suppose with matched rims it would be easy, but I've always had alloy wheels and a steel spare, and yet I can still do my own rotation in the garage if I leave the spare out of it. And since spare rotation with an unmatched spare then requires breaking two sets of tires off the rims with every rotation, I would think the lost time at the tire shop and risk of wheel or tire damage every 3-5k miles would easily outweigh the benefits of obtaining even wear for a tire that you shouldn't be driving for long distances anyway (i.e., get to the tireshop ASAP so you're not driving around without a spare).
He who laughs last, laughs first next time.