W10 is because no one was accepting even numbered Windows releases ... (who remembers using Windows 4?)
As for the free period ... I read somewhere a person has months to get it, like through the rest of 2015. But the down side is that say you upgrade from Win 7, your W10 license will 'expire' when Win 7 goes into retirement (no more Windows support like the recent demise of XP support). Then you'll be forced into the Annual Rental mode like Office 365 has done (I'm guessing here, but pretty sure by inference that's how W10 licenses work).
Windows 8.0 is unusable on a desktop (IMHO), and 8.1 is barely usable on a desktop. A new notebook came with 8.0. Wasn't usable. Upgraded to 8.1. Barely usable. However, HP has no support for the notebook for the available free downgrade to Windows 7. Uggh. If the notebook had a touch screen it might be a bit different...
In 8.1 MS added access to the desktop, but you have to know to right click the little Windows icon where Start used to be. But that doesn't work when a Win 8 app is running. Closing a full screen W8.x app requires an odd mouse gesture that isn't in any manual: using a different machine, I had to Google how to close the control panel. Click the top of the screen (where ever you can find space not occupied by controls or links) and drag down.
Windows 4 did not sell well in China. (Unlucky number.)
The license agreement for Europe (as in DocWils) may differ from the US.
I stopped the triggers in Task Scheduler; and killed the GW Process.
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