Since Microsoft is cancelling its TechNet subscriptions, I have bought the retail version of Windows 8.1 Full version.

I would like to keep my current Windows 8.1 environment with all programs, settings and documents on it (at least for now).

I have tried the steps in article 'How can I change technet product key to retail product key?' (*unable to post link*) to change the productkey to the retail one, but this doesn't work; the activation cannot take place.

How can I change this key without having to reinstall Windows and all my software on it?

EDIT
In some other posting on a different site I read:

Open a command prompt as an Administrator.

• 1. Enter slmgr /upk and wait for this to complete. This will uninstall the current product key from Windows and put it into an unlicensed state.

• 2. Enter slmgr /cpky and wait for this to complete. This will remove the product key from the registry if it's still there.

• 4. Enter slmgr /rearm and wait for this to complete. This is to reset the Windows activation timers so the new users will be prompted to activate Windows when they put in the key.

  This should put the system back to a pre-key state.

  Does this maybe help/solve this?

• Edited by Wouter Haarhuis 20 hours 32 minutes ago

Hello,

As long as the editions are the same you should need to run>

slmgr /ipk xxxxx-xxxxx-xxxxx-xxxxx-xxxxx

do not use slmgr /upk, it is not needed and can cause problems under certain conditions

you do not need to run slmgr / cpky, this simply removes the registry key values where the key is stored, this has nothing to do with changing the key.  This is a security  prevention so the key would no longer be exposed in the registry.

slmgr /rearm is not needed either, when you change the key you will need to reactivate and will be prompted to do, or it may activate on it's own.  so there isn't any need to rearm the machine.