Remove the turkey from the refrigerator 45 minutes before you are ready to cook it so that it can come to room temperature.
Mix the butter with the seasoning packet. Reserve 2 tablespoons of the seasoned butter for the glaze and rub the remaining 6 tablespoons all over the turkey, inside and out, as well as under the skin. Cut the pear into quarters and put them into the cavity along with the herbs. Tie up the legs and put the turkey, breast side up, onto the rack in a roasting pan. Pour 1/2 cup water into the pan and roast for 2 1/2 hours, basting with the pan juices every 15 minutes, while you prepare the glaze.
In a small pot over medium-high heat, add the pear nectar. Cook, stirring frequently, until the nectar is reduced by 1/3, about 10 minutes. Remove from the heat and stir in the reserved 2 tablespoons seasoned butter. When the turkey has cooked for 2 1/2 hours, start basting the turkey with the glaze every 15 minutes until the internal temperature is 165 degrees F in the thickest part of the thigh. If the turkey starts to brown too quickly, cover with a piece of aluminum foil. Remove the turkey from the oven, give it one last basting, and let it rest for 15 to 20 minutes before carving.