I know MS allows to revert back to 7 within a month after an upgrade to 10, will it revert to 7 or 7 with service pack 1?
Is there away to guarantee eligibility for a free windows 10 license for a clean install without an actual upgrade of current win7 system?

The upgrade process keeps a copy of the previous Windows installation, so you will go back to whatever patched state you had.

The only official route is to upgrade from within the previous operating system and then optionally return to the old operating system afterwards (there might be some way around this but I have not looked into that).

Note that the Windows 10 upgrade notifications will apparently be removed after July 29, so if you did return to the old version and wanted to upgrade again beyond that date you would start the upgrade from Get Windows 10 instead.

On my Windows 7 laptop, I simply unticked "Recommended updates", but still installed the security and critical ones. No problem with regard to being nagged to upgrade to Windows 10.

If Microsoft would just have allowed us to run a validation tool that registers our hardware for the Windows 10 upgrade and the let us proceed with a clean install to a new SSD, I would personally have installed it on over a dozen computers by now.

But because they insist that I need to download the upgrade separately for each computer and then install it beside the existing OS before I can finally replace the drive and do the clean install, I have not upgraded a single PC to Windows 10 as I have better things to do than be stuck on a friend's house for who knows how many hours waiting for the download to finish when I should have been able to just switch his HDD with a new SSD, put the installation CD on the disc drive and have the system ready for use in a far more predictable timeframe.

Windows 8 also needs to be upgraded to 8.1 before the Windows 10 upgrade can be installed, so I ended up installing a spare copy of Windows 7 on my notebook's new SSD instead of doing an unnecessary double upgrade.

Since you aren't wanting to do an in-place upgrade you can streamline the process. Swap to the new drive and do a fresh install of the base OS from Windows 7 SP1 or Windows 8.1 media, check that it has activated successfully, then run the Windows 10 setup from within Windows (made with the Windows 10 Media Creation Tool). You will still go through two OS installs, but this is much faster than upgrading an old drive you aren't going to keep. When upgrading to Windows 10 you have the option of keeping nothing which will also install a bit faster.

You can get suitably updated installation media from Microsoft's site (Windows 7 SP1, Windows 8.1). The Windows 8.1 installer accepts both 8 and 8.1 product keys. Windows 7 is only supplied as an ISO, but you can optionally put it on a flash drive with the Windows USB/DVD Download Tool. If your Windows 7 edition differs you can delete or disable ei.cfg on the DVD/flash drive to get a list of editions during setup.

Maybe I give that 8.1 offline install option a try on my notebook and then decide whether I can bother to upgrade it to Windows 10 just to have it as a refence when I need to help someone else to use that OS.

But thanks to Microsoft's heavy handed tactics on getting the upgrade forced on us, I will not settle for any compromise on my Windows 7 computers. Either a clean install is made possible without upgrading first over a previous OS or I don't consider the Windows 10 upgrade free enough be worth the effort that is needed to get me the same sense of control over my OS that I have with previous versions.

Also... There is a free program you can install that will assist you in stopping Windows 10 from installing. It's called "GWX control panel". I don't use it, but I've tested it and installed it on friends/family machines.

Yeah, as someone who had to upgrade a laptop with (originally) a tiny and slow 5400rpm hard drive from Vista to Win8 to Win8.1 to Win10, I understand you. The I had to re-download the ISO half a dozen times because of Microsofts badly made download tool...

Uhm, a clean install with a Windows 7, 8 or 8.1 key has been possible ever since Windows 10 v1151 was released in November 2015. Create a boot medium with the Windows Media Creation Tool, do a clean install, activate with Windows key...easy as a really easy thing.

Well, they could have made it easy from the start (like it was with Vista => Win8.0 IIRC), would have saved quite a few headaches!
Also removing direct download links to the various previous Windows ISO's was a bad move on their part... (I don't think it was a coincidence that it happened shortly before Win10's release...)

No. It's so difficult it takes two brains' worth of power to even begin understanding the process.

Only genius can possibly do such incomprehensible feat.

Therefore, bitching about Windows 10 being scum, evil, stealing passwords, stealing wife and firstborn is much easier.

:D

Granted, intuitively obvious they are not... The upgrade window hasn't closed yet. But tests have shown that at the moment, you can run/re-install a Windows 7/8 copy parallel to a Windows 10 copy activated with the same product key on the same PC, as dual boot, or on an entirely different rig. Or multiple different rigs.

You do not have to use roll-back to be able to do so.

Apparently I forgot to reset the previously searched word combinations in my mind and proceeded to overthink something that would exclude all the "how to disable the Windows 10 upgrade notification" articles without coming up with zero results.