Do I have to create a new API account on google cloud everytime?

Hello,

Thank you for reaching out with your question.

You do not need to create a new API account on Google Cloud Console for each website you use the Instant Indexing plugin on. Once you have set up the API account and configured it for one website, you can reuse the same API account for other websites as well.

If you encounter any issues or need further assistance with setting up the Instant Indexing plugin, please feel free to reply to this ticket. We are here to help!

Sources:
Google URL Inspection API Integration in Rank Math
Making the Most of the Analytics in Rank Math
How to Use Rank Math on a Staging Site » Rank Math
Why Google Displays URL Instead of Site Name in SERP? » Rank Math
How to Setup Rank Math SEO Plugin Properly