Both live on your dashboard: one free trial for the whole server, and promo codes members type on your invite page before checkout. A code replaces the trial rather than stacking with it, and 100% off forever creates no Stripe subscription at all.
Turn it on from your dashboard and set a length in days. Everyone who subscribes to any tier after that gets their Discord role immediately and is first charged when the trial ends; a card is still required at checkout, so nothing has to be chased afterwards.
It applies to new checkouts only — turning it on does not give a credit to members you already have. It is one setting for the whole server, not one per tier.
Create a code on your dashboard and a member enters it on your invite page before they check out — not in Stripe’s own discount box, which is switched off so that a code flatpass turned down cannot be retyped somewhere that does not know your rules.
A code takes a percentage off, either the first payment or every payment. You can restrict it to one paid tier, give it an expiry date, cap how many times it can be used in total, and cap how many times one Discord account can use it — which is the limit that matters most when what the code buys is a role.
There is no edit. The discount is baked into something at Stripe that cannot be changed after the fact, so changing a rate means turning the code off and making it again — you can reuse the same name.
If a member redeems a code on a server that also runs a trial, they get the discount and not the trial. Both exist to lower the cost of trying, and stacked they fight each other: a first-payment discount would land on an invoice the trial had already reduced to nothing.
If a code has run out or the member has already used it, checkout turns them back to your invite page with a message rather than charging them full price.
A code set to take 100% off every payment is a comp: there is nothing left to bill, so no Stripe subscription is created at all. The member gets the role and appears in your members list with no renewal date.
A comp does not count toward your paid-member cap; a member on a discounted subscription does, because they are paying something. What happens when you pass the cap is the page for the rest of that.
Edit the tier and save the new amount. Members already subscribed keep the price they signed up at; only new checkouts pay the new one.
Nothing for 7 days — signups keep working and the dashboard counts down. Only then do new checkouts pause; existing members are never touched.
Your dashboard lists every member with their tier, status and renewal date, above tiles for revenue and active subscribers and a breakdown of where your invite-page traffic came from.