Got nothing to do with free will, God has a Purpose and Plan and Yes Satan will be destroyed at the correct time, with all humans who did not follow God "Jesus Christ".
Documented and when it will take place.
Rev 12:9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
Rev 20:2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,
Rev 20:7 And when the thousand years are expired, Satan shall be loosed out of his prison,
Rev 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
Rev 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.