Set of scripts to get and toggle Azure Hybrid Use Benefit / Standard licensing - http://blog.superautomation.co.uk/2017/07/convert-azure-windows-virtual-machine.html
WARNING - The Set-AzureRmVmLicenseType.PS1 script has to destroy your existing VM and recreate a new VM based on the old machine spec. DO NOT use this on a machine that you have not backed up.
You should check your boot diagnostic account on the VM. If it is ZRS somehow, the script won't be able to recreate your VM.
Should now work with Managed Disk VMs.
Log in to your Azure account and select a subscription. If you need the AzureRm Cmdlets, run 'Install-Module AzureRm'
PS> Login-AzureRmAccount
PS> Select-AzureRmSubscription -SubscriptionName MySubscription
Get a list of VMs and their current license type - Windows_Server is the hybrid use license type.
PS> .\Get-AzureRmVmLicenseType.PS1
Set a VM to hybrid use benefit
PS> . .\Set-AzureRmVmLicenseType.PS1 -VmName testvm1 -LicenseType Hybrid -Force
Set a VM to regular licensing
PS> . .\Set-AzureRmVmLicenseType.PS1 -VmName testvm1 -LicenseType Standard -Force