Can I do a clean install now and keep my license ?

Yes you can completely wipe the drive and all partitions
Clean install windows 10
when asked for product key - just Skip - do not enter any product keys..
the activation for your PC has already been recorded on the MS server

Kyhi said:

Yes you can completely wipe the drive and all partitions
Clean install windows 10
when asked for product key - just Skip - do not enter any product keys..
the activation for your PC has already been recorded on the MS server

That doesn't really make sense. How can they recognise my PC if it is just like a new one (HDD wiped) ?

By the PC Hardware and product ID

Kyhi said:

By the PC Hardware and product ID

"product ID" ? (It's a custom built PC)

Marron said:

That doesn't really make sense. How can they recognise my PC if it is just like a new one (HDD wiped) ?

Windows 10 scans the various components of your computer such as motherboard and cpu and calculates a hardware ID based off what it finds. It does this every times it starts. If none of the major hardware has changed, the hardware ID will be the same and Windows will stay activated. The activation based upon that hardware ID is also stored on Microsoft servers. On a clean install, Windows 10 will calculate the same hardware ID because the hardware is the same. Since it is not activated it looks on the Microsoft activation servers for the previously stored activation based on that hardware ID and if it finds the previous activation it will activate.

Either an upgrade install or the manual entry of a retail product key for Windows 10 will allow it to activate initially and store that activation on Microsoft activation servers for future activations of the same hardware. You change the motherboard - Windows 10 starts and calculates a different hardware ID than what it did before - it deactivates and looks for the new hardware ID on the Microsoft activation servers. It doesn't find it so it won't activate until you call Microsoft and explain what happened and they allow the new hardware ID to be stored on the activation server and you get activated.

Every computer will produce a unique hardware ID because of the unique serial numbers and MAC addresses of motherboards, CPUs and network adapters that Windows 10 can read.

The Answer is YES, you can keep your activation and do a clean install, as long as the prior activated build was 10240