tramadol?

Ok so I just wanted to know if tramadol is addictive. My fiancée used to have a pill addiction, but after he met me decided to change he went to rehab and he's been clean for two years now. He has bad back pain and nothing works for him. He did everything the doctor told him to but they found nothing wrong. One day we were at my grandmothers house and he was in a lot of pain so she gave him a tramadol to help him with the pain before he went to work. It helped him a lot and would take one when he really needed it. Now for the past month he's been taking it almost every single day. My grandmother gave them to me for him so I give him one when he asks but it's every day almost.. Is tramadol addicting? I need to know if this is becoming a problem so I can stop it.