Those of you that upgraded to Windows 10, have you noticed your authorized devices list on Google Play Music populate with multiple "Google Play Music for Chrome on Windows" authorizations?
I use the browser to stream music and upload music (don't download). I noticed since I upgraded to Windows 10 on my Surface Pro 3 on July 29, that 5 out of my 10 slots have been used up with "Google Play Music for Chrome on Windows" authorizations. Google was able to do a courtesy de-authorization of all devices. I'll be monitoring this more often as I only use ONE PC: my Surface Pro 3. My account requires two-step verification so no rouge PC should technically be accessing my account.
The dates of "signing in" on the "Google Play Music for Chrome on Windows" seem to coincide with major Windows 10 batch updates since the official launch. Google told me that any Windows ID changes, Incognito browsing, and factory resetting uses up an authorization slot when signing back in. I don't browse incognito, I haven't done 5 factory resets either. Today another slot was used up as a "new sign in". I restarted my PC last night because of updates that were installed. Perhaps that could be the culprit if it modifies the Windows ID.
Welcome back! That's an interesting possibility, and I wouldn't be surprised at all if each Win10 update was being considered a new installation and therefore a new install. Let me check my setup.
EDIT: I did see a couple of authorizations for my Windows 10 desktop, only about 10 days apart this month. I can't be sure when the updates came, though. Will keep an eye on it. It would be worth sending Google some feedback on this--you can do it through the Play Music app.