First of all, Microsoft has done very well to provide the installation media in ISO format - both in the few versions of Windows 10 and the more numerous versions of Windows 8.1. It has also removed the obstacles with a Windows 8 OEM Product key not working in a Windows 8.1 upgraded computer. Now, this particular computer never had an issue with upgrading to Windows 10 previously. The upgrade was accepted and activated. To clarify, Microsoft has no problems accepting that the computer is now running Windows 10 and will be supported for the rest of its lifetime as a Windows 10 computer. The activation was done automatically, with the Product Key generated and kept within the cloud, with no information for the user, in terms of e-mail or otherwise.
Now it seems a bit counterintuitive......Acer's Product Support Website (and other manufacturers' too) has downloads of some drivers, such as VGA Graphics drivers, BIOS updates (which are rarely done except in emergencies - which I had with an Acer Aspire V5-132), and some network drivers which are already incorporated in Windows 10. But it doesn't have downloads of OS's. So you would have to inquire, and have a few back-and-forth e-mail exchanges before they actually know what you need. And most common users and those who have upgraded to Windows 10 wouldn't even know they had Windows 8.1 Single Language with Bing unless they had kept the packaging - or perhaps the sticker is in the screwed-in battery compartment.
In terms of Acer, the Acer product Support Website (if you had registered your computer with them previously) provides a page that introduces it's computers' users to the 1 year free upgrade offer to Windows 10, but that page's links leads back to Microsoft's download page. As an argument, you wouldn't expect users to contact Phoenix Bios to get their BIOS update after major technical issues with a computer, though some do - they have an associated online store,......but Windows 10 was always known as a Microsoft initiative with minimal support from the manufacturer's Product Support/Help page. If Windows 10 already worked and was activated with a Digital Entitlement, it is counterintuitive to expect a user (in a developing country with much less disposable income) to pay for a recovery disk or Installation Media for an out-of-date OS, just so that they can once again upgrade to Windows 10, that they once had a Digital Entitlement to, but not anymore, and with the passage of the 1 year amnesty (or whatever you call it), will probably have to pay for Upgrade rights to this Windows 10 OS that they previously had. And Windows 10 is also contributing to it by their Refresh and Reset options in the Recovery menu not really working for computers that have been upgraded this way. Unless you define the rest of a lifetime of a computer as the period in which it hasn't been reformatted, and these computers are resurrected "Lazarus" computers. One solution is to buy a Windows 10 installation media, but it's a rather ugly solution for the tech oriented. The OEM bios Product Key is one that we would assume is resistant to hacking, in a way that an installation media Product Key wouldn't, I assume.
Microsoft may have got a bad deal with the licensing offer for Windows 8.1 Single Language with Bing OEM installation, but it is not the role of the consumer to sweeten this bad deal for Microsoft by purchasing new original Installation media, however wonderful Windows 10 is. Ubuntu version of Linux is pretty nice too. Computers coming with an OS already installed, whether with installation media as in the early 2000s, or without installation media, in the last few years, is now an accepted principle. I don't think Microsoft would drop all their OEM OS deals now, and depend on their own marketing of Windows 10, so why should consumer have to? These are just my opinions based on doing some tech OS installations for family members and myself, and being a bit obsessive about tech.