If you ever need to know the Office 365 licenses purchased by your organization or you just need the SKUPartNumber, here is a quick way to get it via PowerShell.
Get-AzureADSubscribedSku | Select SkuPartNumber
Here is what the output looks like. List of SKUs depends on the licenses you have purchased.
To get a summary of license consumption and look at the available licenses, just run the below command.
Get-AzureADSubscribedSku | Select -Property Sku*,ConsumedUnits -ExpandProperty PrepaidUnits | ft
Here is what the output looks like.