We know that "God is love" (1 John 4:16) and we might think of a loving God as always being open to forgiving a sinner who repents. The case of Satan is of course unique. Satan was created as a beautiful angel, close to the Heavenly Father. He tried to challenge the Almighty Jehovah. Satan sinned willfully, with full knowledge and understanding. He knew what he was doing. In making the choice to rebel against God, he sealed his fate. Jesus describes this in Luke 10:18 "…I beheld Satan as lightning fall from heaven."
Psalm 89:14 tells us that "Justice and judgment are the habitation [foundation] of thy [God's] throne." Justice is the core of everything God is and does. We know that God cannot make a mistake: "As for God, His way is perfect," Psalm 18:30. The consequence of Satan's sin is absolute. He will not be forgiven. We think that Satan would not ask for forgiveness in any case because he and evil are one and the same. He is uniquely, absolutely, unchanging evil.
God's love was shown in giving His Son to provide a ransom for all mankind born in sin because of Satan's introduction of sin on earth in the Garden of Eden. Though God permits Satan to have power during the present night of sin, it is for the purpose of educating men so they will choose good in Christ's future earthly kingdom. Satan will have no power then. Revelation tells of Satan's end – "the second death (Revelation 20:14)" in "the lake of fire (Revelation 20:10)." This destruction for all eternity will occur at the end of the Millennium of Christ's earthly kingdom. We are thankful for God's complete plan to bring mankind back to the original relationship that Adam had with God before sin came to earth.