Need usage breakdown for deleted API keys for customer billing

Hi everyone,

I’m wondering if anyone has dealt with a similar situation before.

We are an external development company managing multiple client projects under a single OpenAI Organization.

For one client, we need to provide supporting documentation for their API usage and costs. However, we’re running into a limitation with the Usage Dashboard

• One API key dedicated to the client project has already been deleted , so it can no longer be selected in the Usage page.
• Another API key belonging to a different project was created under the same OpenAI Project, making the project-level usage unsuitable as evidence for the client.

Ideally, we’re looking for historical usage for the following period

• 2026-05-01 to 2026-07-01

Specifically, we’d like to obtain a usage breakdown (cost and, if possible, input/output tokens) for the relevant API keys.

Has anyone successfully obtained this kind of historical data from OpenAI Support, especially for deleted API keys?