Windows 10 Activation - Microsoft Community

my current pc running windows 7.

i upgraded windows 10 during free upgrade period.

after upgrading pc / windows 10 activated.

after using pc few months did clean install of windows 10.

the pc / windows 10 still activated , have been using since.

now  i want install windows 8.1 on pc short period.

i have retail version of windows 8.1 , activation product code.

my question is: if install windows 8.1 on pc , activate using product code came it, @ later time able clean install of windows 10 on pc , have automatically activate.

yes.  activated "good-for forever-on-that-device" digital license windows 10 when upgraded, can reinstall windows 10 @ time on device; when do, should activate automatically shortly after installation long have active internet connection.

Windows / Windows 10 / Install, upgrade, & activate / PC