If the spare is of the same type and rating as those already fitted, in proper condition and properly inflated, it has the same performance limits and life as the others. Indeed, it is or was recommended practice to swap the wheels around at intervals, including the spare, to even out tyre wear.
It is only types specifically intended merely to get you home or to a tyre-fitters, that may have speed and distance limits, and I would think they should be defined in markings on them, in literature supplied with them or be in the vehicle's owner's handbook.
I do not understand the point of such spares. I think it wrong of manufacturers even to make them.
(Use one of those foam-injection fillers, and you write even an otherwise-repairable tyre off completely.)
As for being towed home, if a spectacle-plate tow, not a fully flat-bed recovery, then if the flat is one of the rear wheels it would need be changed, or at least exchanged with one of the front ones, anyway.