Your object would have 2 completely separate motions:
- Its horizontal movement. In the absence of air friction it will keep that movement unchanged.
- Its vertical movement. Even if it was stationary (vertically) when you launched it, as soon as you release it it will start falling with an acceleration of $9.8m/s^2$. So after $1s$ it will be travelling downwards at $9.8 m/s$ and it will keep accelerating.
As a result the object will follow a parabola in which it moves at the same speed horizontally until it finally hits the ground. So no, it will not stay up and "maintain flight".
Newton was the first to illustrate this will the thought experiment of a cannonball being launched at faster and faster speeds, until it finally goes so fast that it "falls" right around the earth. Which is how satellites stay in orbit: they are always accelerating to the earth at $9.8 ms/^2$ (actually a little less because they are further from the earth than we are) but they are moving at $7.8 km/s$ so they continuously miss the earth.