@dai.ishida Welcome to Microsoft Q&A Forum, Thank you for posting your query here!
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PromptFlow traces stored as part of collections in Azure AI Studio are retained for up to 30 days. This retention period helps in detecting and mitigating abuse while ensuring the security of the stored data.
More info here: https://learn.microsoft.com/en-us/legal/cognitive-services/openai/data-privacy#preventing-abuse-and-harmful-content-generation
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Hope this helps. If you have any follow-up questions, please let me know. I would be happy to help.
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