I use spare just for spare-I don't rotate them in. Rarely have I ever put more than a couple hundred miles on a spare tire, and usually much less. If it were mine, I'd check the date code and confirm it is 7 years old. If so, I'd keep it another year or two. If it was pushing 10 years I'd replace it.
Tires fail from flexing, heat and age. Take away the road fatigue, the tire is diminished from age only. I think if it was stored out of sun and carried proper inflation pressure at time of use, it would be good for a few hundred miles if it was 7 or 8 years old.