Tricyrtis 'Empress' is a T. formosana selection that has somewhat larger flowers than the species and is cold hardy to Zone 6(at least). It will do fine in a pot, overwintered outdoors in Zone 7. As is is an early blooming variety(July-Aug).the foliage emerges very early in the spring and it will need protection from a late freeze or frost. Be aware that Slugs also love the tender new foliage. It doesn't tolerate long periods without moisture, but can be allowed to dry out between watering.
They increase rapidly by short stolons and can usually be divided into multiple plants each year.
Enjoy your wise purchase, plant in a shady location(or grow them in pots) and be forewarned that Toad lilies are addictive! (I started with one and now grow many species and varieties that have multiplied into the hundreds)
Rb

Thanks a lot RB. This particular one that I have purchased is still blooming and has more buds. I repotted it this morning into a little bigger pot and have place it in a mostly shady spot. Will this die back during our zone 7b winters? From your post it sounds like it will.

Yes, all of the the Tricyrtis go dormant after the first heavy frost or freeze. Since you mentioned yours are still in bloom, I checked mine and some of them still have a few blooms. Those are mostly hidden, in a somewhat dry area, under a Beautyberry and Weeping Buddleja, which are under deciduous Magnolia amd Sourwood trees. Frankly, I was surprised to find any blooms left!
Rb

What do you think would happen if I put it in the greenhouse until spring and it didn't go dormant? Bad? Good?

Probably not a good idea. All herbaceous perennials need a period of R & R to remain healthy.
Rb