Why if it is fully offline then why does the micro-controller need a license key? What does it use the key for? How can any monitoring/analytics take place?

I read the article and was interested but after clicking around the site I was thoroughly confused about billing/pricing/metering.

Picovoice runs on almost anything: web browsers, mobile, desktop, single board computers, and microcontrollers. For the platforms that have connectivity (i.e. almost anything aside from microcontrollers), we do call home for license management. This helps us keep the `Free Tier` free for personal users, hackers , and skunkworks projects, but make sure we get paid by enterprise customers with deployments at scale [1]. On a microcontroller like the one in this tutorial, there is NO connectivity option. Hence, in this specific case it is 100% offline with no license management. In other cases voice recognition is 100% offline but the call home for license management needs connectivity.

[1] https://picovoice.ai/pricing/

Then please explain the

> Picovoice engines call home servers to stay active and report the consumption for billing purposes only.

It sounds like he's saying that the key is hashed offline to check for validity, and doesn't actually verify it via server.

Yes, the board does not have a connectivity chip of any sort [1]. Even if one really wants to there is no way to connect to anything from this board.

[1] https://www.st.com/en/evaluation-tools/stm32f4discovery.html