Microsoft improved their business a lot and they are still offering a free Windows 7 to Windows 10 upgrade. This is wonderful news for outdated PCs that have a valid Windows license.
The link to download is here:
https://www.microsoft.com/software-download/windows10
You could also just download the ISO:
https://www.microsoft.com/en-gb/software-download/windows10ISO
Caveats
Windows doesn’t support all kinds of older TLS protocols anymore, so you might run into various problems, e.g.:
0x80072f8f - 0x20000
The way to go to get around this problem temporary is to re-nable TLS 1.1 and TLS 1.2. This will also fix Outlook 365 from starting up properly.
Save this using notepad with an extension .reg:
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp] "DefaultSecureProtocols"=dword:00000a00 [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp] "DefaultSecureProtocols"=dword:00000a00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client] "DisabledByDefault"=dword:00000000 "Enabled"=dword:00000001 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client] "DisabledByDefault"=dword:00000000 "Enabled"=dword:00000001
Now right click and open that file.
Older versions of TLS is enabled again and you can continue to try and upgrade your computer.