Instructions:
Activate Windows 10 Professional without a product key:
Step 1: Run Command Prompt as administrator.
Step 2: Execute the following 3 commands separately and press enter at the end of each line.
slmgr /ipk VK7JG-NPHTM-C97JM-9MPGT-3V66T
slmgr /skms kms.xspace.in
slmgr /ato
Step 3: Press Windows + R key to bring up the Run dialog box and type "slmgr.vbs -xpr" to confirm whether your Windows 10 is activated or not.
Then reboot.
Otherwise:
slmgr -rearm
Will give a bit more time...
slmgr /dlv
Will show some info....