LicenseUnity.ps1

function Install-UnityLicense($user, $pass, $key) {
    $programDataDirectory = "C:\ProgramData\Unity"
    $unityProgram = "C:\Program Files\Unity\Editor\Unity.exe"

    # Attempt to Return License first
    Start-Process -FilePath $unityProgram -NoNewWindow -Wait -ArgumentList '-batchmode','-quit','-returnlicense'

    # Delete programDataDirectory
    Write-Output "-- Checking if path $programDataDirectory exists"
    If (Test-Path $programDataDirectory){
        Write-Output "Removing $programDataDirectory"
        Remove-Item -Recurse $programDataDirectory
    }

    #Launch Unity
    Start-Process -FilePath $unityProgram -NoNewWindow
    Start-Sleep -s 15
    Stop-Process -processname Unity

    #License unity with provided username, password, and key
    & $unityProgram -batchmode -username $user -password $pass -quit -serial $key
    Start-Process -FilePath $unityProgram -NoNewWindow -Wait -ArgumentList "-batchmode","-username $user","-password $pass","-quit","-serial $key"
}

Install-UnityLicense user@email.com password SERIAL-KEY-HERE