If satan was damned to hell...?

how come in the book of job he's up in heaven making a wager with god that he can make job curse god? also, why does god let him out of hell and torment people on earth? you can't use the free will excuse either. if you're damned to hell for all eternity, you should be in hell, not on earth. if you get sentenced for murder on earth, they don't let you out for good behavior.