I think applying appropriate credits for artists is wise, shows humility, and will be favorable for you and the composer in the end. If you want to uphold a positive reputation with respect, showing the dignity to those who contribute is wise. I have been creating music for games and have multiple studio albums on the market. I ensure all musicians that I work along side receives their fare share of contribution and credits for their shining moment. Lesson to be learned, my friend.
Lot's of love,
Tony