the ability to reward referrers with free credits

The affiliate program should provide the admin (website owner) with two options: either give referrers a commission on purchases made through their referrals (which is already available), or offer them free credits such as (a free number of words, images, or speech-to-text...) for every successful referral. This allows the website owner to choose what they want to offer to referrers. Personally, I prefer to give referrers free credits instead of a commission on purchases made by the people they refer.