@Purbasha Welcome to Microsoft Q&A Forum, Thank you for posting your query here!
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Firstly, apologies for the late reply.
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The News Search API v7 headers REST API reference article, clearly mentions that the Ocp-Apim-Subscription-Key is a Required
field. So, if this auth header is not specified, you cannot invoke the Bing News Search API.
Hope this helps. If you have any follow-up questions, please let me know. I would be happy to help.