Hello @Gus Ho , Thanks for using Microsoft Q&A Platform.
Yes, you can use the audio output from TTS for commercial purpose, as long as you are using a valid standard(paid) pricing tier such as Pay-as-you-go tier. There is no special license or authorization required for the usage of this service output. But please comply with the code of conduct: Code of Conduct for text-to-speech integrations | Microsoft Docs.
I hope this helps.
Regards,
Vasavi
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