“Hey, now this part of the product is paid — since you were there since the beginning, here's a 40% discount code that you can use for life.”

When you flip free to paid, grandfather early users with a lifetime discount

Free beta features were tagged with a Pro label warning users they would eventually become paid. When the paywall went live, longtime users got a lifetime discount code as a thank-you, softening the transition from free to subscription and protecting goodwill.