“Keep in mind that these Windows VMs expire after 90 days, so youll have to re-download periodically.”
You don’t need to download the file again.
simply remove the expired one and reinstall the download file 90 days ago.
those file rarely change.
Better than that, just take a snapshot before you activate the demo. That way, you simply roll back to the newly installed snapshot every 90 days. This is Microsoft’s advice.