Codes and offers
Checkout coupons, founding lifetime into Pro, Affiliate in the user menu
Billing checkout asks Have a coupon code? Stripe promotion codes are allowed.
A one-time founding deal can grant Pro. That is not a fifth monthly plan. After it lands you are on Pro, next to Creator / Growth / Ultimate like anyone else. Lifetime deal can appear in the user menu when that offer is on.
Leaving a paid plan can offer a retention discount. Affiliate, when it is configured, is an external link in the user menu. It is not a Settings row.