Satan is an angel. Angels are pure spirit. Angels exist not in the temporal plane like we do, where there is a ‘before, during, after’ and where time is measured in such, but in an eternity which is like an endless ‘now’. What Satan (with free will, full knowledge, understanding, and consent) chose ‘from the beginning’ will endure through eternity. He was given exactly the same chance that human beings have; the only difference is that his chance (choose God or reject God) was made in a construct ‘outside’ time, and our choice is made in a construct ‘in’ time.
Our choice in time, before our death, will have the same result. WE will, in eternity, no longer choose to change because we will have already made our ultimate choice. . .just as the angels did.