<script>
	$(document).ready(function(){

	    if(localStorage.getItem('primaVisita') != 'true') {
	        localStorage.setItem('primaVisita', 'true');
	        $('#popupBonomi').show();
	    } else {
	        $('#popupBonomi').hide();
	    }
	});
</script>

Per rimuovere il valore:

localStorage.removeItem('primaVisita');