"Yea, and are willing to mourn with those that mourn; yea, and comfort those that stand in need of comfort, and to stand as witnesses of God at all times and in all things, and in all places that ye may be in, even until death, that ye may be redeemed of God, and be numbered with those of the first resurrection, that ye may have eternal life." Mosiah 18:9.
To me this teaches that indeed taking his name upon us is for all eternity, it says "stand as witnesses of God at all times and in all things, and in all places....." What a blessing for us to always have His spirit to be with us. I am so grateful for the simple profound Doctrine of Christ.
I believe it was Elder Packer who taught that a study of the Doctrine would change behavior faster than anything else. More than a study of behavior, a study of the Doctrine of our Savior would change behavior because as we seek to become what He wants, needs, hopes we will become, our nature will change.