Promo codes and bonus credits are related, but they aren't the same thing.
Promo codes are codes associated with promotional offers. Each promotion may have its own eligibility requirements, redemption limits, and expiration date.
Bonus credits are promotional credits added to your account when you qualify for an applicable offer.
Once bonus credits are issued, they expire 30 days after they are issued and can be used on eligible bets.
You can check your available bonus balance in your account.