It does appear to be an agave. Most agave plants are hardy to zones 7b, so it should be fine over winter in your area, though you may want to give it some additional protection in severe weather conditions. Generally, however, many of the species are quite hardy, even to temps below 10 F. To err on the safe side, since you don't know the exact type, you may want to stick it in a container where you can move it to a more sheltered location over winter. - They are relatives of yucca, which I have in the garden here in NC and it takes our winters just fine.
Here is more info: https://www.gardeningknowhow.com/ornamental/cacti-succulents/agave/growing-agave.htm