see Efficiency Guidelines.

If you have an API key account since more than a month and you have not made sales with it, Amazon could have just kicked you off the API usage.

From January 23, Amazon denies API access to accounts without sales in the last 30 days.

Refer to this page for more information
https://docs.aws.amazon.com/AWSECommerceService/latest/DG/TroubleshootingApplications.html#EfficiencyGuidelines

Say thank you to Amazon.

Sometimes it is the same when you have sales I have only some, but I have, and still doesn’t work for me since december. Yeah best timing. I think I could have more sales if the plugin had been working properly.

Or maybe they also have an amount minimum?

And hey, with the new sales percentages changes it is getting worse :(. Now if they don’t buy the exact product you are linking, you get less.