Some foxgloves are perennial. Check a seed catalog or book and
see what it says about yours. It may or may not be right.
Either kind will self-seed if you don't dead head. Perennial
ones have come back fine for me even leaving the flowers on. They look
sort of raggedy though. If the weather is right next spring you should
see lots of seedlings which you can move where you like. Hybrids will
not breed true of course.