Hi Pete,
unfortunatelly Automatic Virtual Machine Activation (AVMA) is only available if your hypervizor/physical host system is running (Activated) Windows Server 2012 R2 Datacenter Edition with Hyper-V role installed.
Then you can benefit from automatic activation of Windows guests (Windows Server 2012 R2, STD, DAT, ESS) hosted at this Hyper-V server.
So its strictly MS "hypervizor" feature ...