User Office365 Licenses using PowerShell. Associated blog post can be found here https://blog.darrenjrobinson.com/adding-removing-user-office365-licences-using-powershell-and-the-azure-ad-graph-restapi/

UsersLicenses.ps1

<#
   Get Active Users
#>
$Search = Invoke-RestMethod -Method Get -Headers @{
    Authorization   = $authenticationResult.CreateAuthorizationHeader()
    'Content-Type'  = "application/json"
} -Uri ('https://graph.windows.net/{0}/users?$filter=accountEnabled eq true &api-version=1.6' -f $authenticationResult.TenantId)

# Work out which ones aren't assigned the license we are looking to assign
$userlicensed = $false
$unlicencedUsers = @()
$licensedUsers = @()
foreach($user in $search.value){
    # check license against users licenses
    foreach ($license in $user.assignedLicenses) {
        if ($license.skuId -eq $LicenceToAdd){
            $userlicensed = $true
            $licensedUsers += $user.userPrincipalName
        }
    }
    if (!$userlicensed -or !$user.assignedLicenses ){
        #Exclude the AADConnect Account
        if (!$user.userPrincipalName.StartsWith("Sync_")){
         $unlicencedUsers += $user.userPrincipalName
        }
    }
}