Pete Doherty has admitted he will never be able to stop taking drugs.The junkie rocker - who had to promise his supermodel fiancée Kate Moss he would stay clean before she would agree to marry him - has confessed he can't live without narcotics. Speaking on BBC documentary series 'Arena: Pete Doherty', he said: "Abstaining isn't really my thing. I don't think I'll ever give up drugs."But I do know I don't think I can keep smoking crack anymore. Not just because of the police, but because it was fucking my life up. "Pete, 27, was admitted to London rehab clinic The Priory in August where he received treatment for heroin and crack cocaine addiction. After a string of arrests and court appearances he recently passed a court-ordered drugs test and was commended by a magistrate for his efforts to clean up. However, since he left rehab to tour with his band Babyshambles, Pete has been partying hard and allegedly assaulted a photographer in Italy. Last month, Kate, 32, confirmed she is engaged to the bad boy musician. The couple plan to tie the knot on her 33rd birthday in January.