Open powershell and run it as administrator.

Enter the following command

Get-CimInstance -ClassName SoftwareLicensingProduct | where PartialProductKey | select Name, ApplicationId, LicenseStatus | Format-List *

Wait for what feels like days

Bam! The information you were looking for!

Thanks goes to Richard Siddaway: https://richardspowershellblog.wordpress.com/2014/04/13/checking-license-activation/

Not working?

Open an elevated command prompt and use the following command

wmic path SoftwareLicensingService get OA3xOriginalProductKey