Hi, I was interested in downloading thermostat data every day via the API (into a spreadsheet or similar) but I read the terms and it says you can’t store data for longer than 10 days - am I reading that correct?
That is correct, although the policy is only for products that require a WWN product review approval. If this is only for personal use, than your product does not require a review as you will not require more than 50 users.
Yes this is only for personal use.
So would an app not get WWN approved if it wanted to store more than 10 days of thermostat data for historic reporting?
Correct, it would not be approved. See 1.14 in the Guidelines: https://developers.nest.com/product-review/product-review-guidelines#1_functionality