how to move on right button and checkbox with bootstrap 4

I made this with Bootstrap 4 and i want to move button and checkbox on right but i really don't know how to do, someone can help me?[

http://ift.tt/2wIDaSW

<div class="col-8">
<div class="form-group" style="text-align:right">
    <textarea class="form-control" id="exampleFormControlTextarea1" rows="3" placeholder="Lascia anche tu una dedica sul profilo di @xdekus">
    </textarea>
    <div class="form-row align-items-center" style="margin-top:1%;text-align:right">
        <div class="col-auto">
            <button type="submit" class="btn" style="background-color: #5EBD63; color:white; cursor:pointer; margin-top:1%;">Invia</button>
        </div>
        <div class="col-auto">
            <label class="custom-control custom-checkbox" style="margin-bottom: 0px;">
                <input type="checkbox" class="custom-control-input">
                <span class="custom-control-indicator"></span>
                <span class="custom-control-description">Lascia la dedica in forma anonima.</span>
            </label>
        </div>
    </div>
</div>