# Billing FAQ
## How does billing work?
Graphene bills per token. Every request records the model, its input and output token counts, and the routed per-token rate; those line up into your usage and are invoiced through Stripe. You pay for what you route — there is no seat licence or minimum.
## Where does the 20% discount come from?
The routed rate is a flat **20% under each provider's published list price**. That headroom comes from orchestration efficiency — batching, prefix caching and routing work to the right tier — passed straight through as a discount rather than kept as margin. It is a flat pass-through, not a volume tier you have to negotiate into.
## How do I manage payment methods?
Use **Manage billing** (the Stripe Customer Portal) from the in-app billing page. The portal is where you add or update cards, view receipts, and manage your billing details.
## Budgets vs invoices
A **budget** is a forward-looking spend cap you set per workspace: when it is reached, further requests are held until you raise it. An **invoice** is the backward-looking record of what you actually routed over a billing period. Budgets prevent surprises; invoices reconcile them.
## What happens if a payment fails?
If a payment fails, Stripe retries according to your billing settings and you are notified to update your payment method through the portal. Resolve the payment method to restore normal billing; budgets continue to govern spend in the meantime.
## Is there enterprise committed-use pricing?
Committed-use and enterprise terms are available on a sales-assisted basis. If you have predictable volume or need contractual commitments, [talk to us](/contact) and we will scope terms with you.