Why should the object be moved at constant velocity when we define potential energy ?

Explanation

If the object does not move at constant velocity, then it will have different velocities at the initial and final locations According to work kinetic enery theorem, the exteme force will impart some extra kinetic energy, we associate potential enery to the forces bike gravitational force, spring force and coulomb force. So the external agency should not import any kinetic energy when the object is taken from initial to final location