I am willing to believe that MS might try a subscription model, but this doesn't look like particularly strong evidence for it. Those strings could be anything

I am willing to believe that MS might try a subscription model, but this doesn't look like particularly strong evidence for it. Those strings could be anything - For all we know, it's just tracking office 365 subscription status/enterprise enrollment, or tracking windows account notification subscriptions, or any of a hundred other valid reasons. Those terms are just too generic to be particularly meaningful.