Should I ask him to get to alcohol counseling or kick him out?
That’s an alcoholic blackout – and yes he can be telling the truth that he remembers some things and not others. You don’t say anything about his previous drinking but alcoholic blackouts are a sign that he is likely somewhat allergic to alcohol – and that’s a tendency that often co-incides with alcoholism. His readiness to promise to never drink again suggests that he’s already aware he has a problem with alcohol. Without counselling/ attendance at Alcoholics Anonymous he’s unlikely to permanently put down the drink so if I was you I wouldn’t believe he’s serious unless he does go get help to stay away from the alcohol. Only you can decide whether to kick him out or give him a chance – with the condition that he gets help. Good luck!