Utilize the bot for free and talk with it for a limited time each day (15 messages a day). To further chat with it, your Discord will require its own OpenAI account (cheap & increases chat usage).
Each time the bot is talked to, it will be billed to that account.
OpenAI provides a $5 or $18 trial and chat usage typically costs less than HALF A CENT per day, subject to usage levels. In the future we'll be able to more easily charge you for chat usage, without you needing to create an OpenAI account