Question

when a falling object reaches a speed called terminal speed, its speed is no longer unceasing. the object id loosing gravitational potential energy nut no kinetic energy. since energy must be conserved where is the gravitational potential energy going 

Answer 1

It's going towards when the object finally hits the ground, where Newton's third law of motion takes effect: All forces have an equal an opposite reaction. So that's the answer. I hope this helps!

Answer 2

It's going to push aside and heat the air through which the object is falling.

The heating is the result of friction with the air, just like when the same object scrapes against anything else. Friction, in general, always robs energy of motion and turns it into heat.