A balance you spend inside the chat. One credit is one dollar — no conversion to work out. Credits are not a subscription: they do not remove promotions and they do not change what the model remembers. That is a plan.
You are not signed in, so there is no balance to show yet. Sign in or create an account — it takes a nickname and a password, and asks for nothing else about you.
Credits are for the companion features — gifts inside a roleplay chat — and those are still being built. There is nothing to spend a credit on today, so we are not selling them. When there is, this page will sell them and your balance will be here waiting.
If you are after fewer promotions and a longer memory, that is on the plans page, and it works today.