Placing ice cubes on the soil will keep the soil moist and prevent the pot from standing in water. Use lights that do not give off heat. Mini-lights are the best for live trees. After the holidays, move the tree outdoors into a protected area out of direct sunlight. In two to three weeks, you can plant it in the garden if the ground isn't frozen, or keep it in its container.
Most evergreens can stay in the same pot for several years.