Force is not at all required for maintaining the motion of a body. Force is only required to kick-start the movement, change the direction or accelerate the body. But we are under wrong impression, because in our environment, air resistance and friction slows down the object. To overcome these resistances, we are forced to apply force frequently.
Railway system use this principle for transportation(friction is greatly reduced in the tracks). Planets and satellites go round for a long time without the use of force. Scientists are trying to make a superconductor in which the resistance is totally eliminated and the current (electrons) will flow for ever.