I have deployed an instance of Windows Server 2016 (with containers) on Azure. When I start the machine I see a message in the right-bottom that Windows hasn't been activated.
Also the settings show that Windows is not activated:
I would guess that these Azure provided images have already been activated?
You could try to resize your VM to other size.
If it does not work, I suggest you refer this official article about troubleshooting Windows activation failures on Azure VMs.