Would a doctor prescribe someone Methadone to get over an Oxycontin addiction?

My boyfriend just got out of rehab from Oxycontin and other pain killer abuse. and i have a feeling heroin as well. I have been hearing things that he has relapsed, and i almost believe it. He says he will be going to the doctors everyday for the next three years to get Methadone everyday to stop the cravings. Is this the right thing? is he lying?

: http://alcoholdrugstreatment.info/would-a-doctor-prescribe-someone-methadone-to-get-over-an-oxycontin-addiction