Rosemary is a Mediterranean plant and a tender perennial. There are some rosemary cultivars that are more cold hardy, but at high elevations it's best to move the plant indoors for the winter. You should consider repotting it into a clay pot with well-drained potting media and situating it in a bright, sunny location in the house. Rosemary is moderately drought tolerant in its native habitat, but does thrive with some moisture.
Continue to use the rosemary sprigs all year long. They will add a bit of summer to your winter cooking.