AIUS runs a fixed set of models through your AIUS account. You never need a key from a model provider. Type /models to choose. Pareto, the default, routes each request to a suitable model.
The Select model list in the AIUS terminal: Pareto (recommended), Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5, GPT-6 Astra, GPT-6 Luna and GPT-6 Sol
ModelID
Paretounion-alpha
Claude Fable 5.1fable-5.1
Claude Opus 5.5opus-5.5
Claude Sonnet 5sonnet-5
GPT-6 Astragpt-6-astra
GPT-6 Solgpt-6-sol
GPT-6 Lunagpt-6-luna
To start with a model: aius --model aius/opus-5.5.

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Who pays

Model requests are billed to your personal organisation by default, the one AIUS creates with your account; there is nothing to set up. To bill another organisation, type /organisation and choose it, or run aius platform organisation <id>. The choice lasts for this sign-in; choosing your personal organisation again returns to the default.
The Model organisation list in the AIUS terminal: Personal (ana.lopez), marked Default, and AIUS Examples, each with its ID
The terminal shows the session’s running cost below the prompt. An organisation’s owner can cap its spending with a shared budget; aius platform credits shows the recorded budgets.