One of the new features in version 1803 of Windows 10 is Activation Inheritance. It's mentioned briefly in this technet blog entry, but without any elaboration. It's also mentioned here. but it's very unclear as to whether you need Windows 10 Enterprise or not. I'm very interested in this, but I have Windows 10 Professional. It was upgraded from Windows 7 Ultimate during the free upgrade period some years ago, so I have a digital license. I've been searching all week but I cannot find anything concrete that explains how to enable this feature, or what I need to do. I did install a fresh copy of Windows 10 (1803) in Virtualbox, but it's not activating on its own. Can anyone point me to some concrete explanation of how this works and what I need to do?
it's very unclear as to whether you need Windows 10 Enterprise or not.
The linked article defines what Activation Inheritance is exactly
Windows 10 virtual machines can be configured to inherit activation from their Windows 10 host
Additional research indicates that Acivation Inheritance works as follows
Inherited Activation is a new feature available in Windows 10, version 1803 that allows Windows 10 virtual machines to inherit activation state from their Windows 10 host.
When a user with Windows 10 E3 or E5 license assigned creates a new Windows 10 virtual machine (VM) using a Windows 10 local host, the VM inherits the activation state from a host machine independent of whether user signs on with a local account or using an Azure Active Directory (AAD) account on a VM.
To support Inherited Activation, both the host computer and the VM must be running Windows 10, version 1803 or later.
The feature is limited to subscribers of Microsoft’s Enterprise Windows 10 E3 and Windows 10 E5 subscription service. In other works, if your eligible Windows 10 Enterprise host installation is activated, then virtual machine running on the machine will also be activated.
Windows 10 Enterprise E3 in CSP is a new offering that delivers, by subscription, exclusive features reserved for Windows 10 Enterprise edition.
Windows 10 Enterprise E5, which includes all the features and functionality available in Windows 10 Enterprise E3 plus Windows Defender Advanced Threat Protection and advanced IT administration management functionality
Since you have Windows 10 Professional, and you do not have an E3 or E5 subscription, you will be unable to use this feature. In your case, a Windows 10 VM, would need it’s own license.
I did install a fresh copy of Windows 10 (1803) in Virtualbox, but it's not activating on its own.
If you had an eligible installation of Windows 10 Enterprise, you would have to use Hyper-V (or Azure VM but I am not entirely sure) not VirtualBox (I know for a fact VirtualBox VMs are not applicable), in order for the guest OS to be automatically activated.