LocalStorage

HTML

<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script>
<select name="purchasableId" id="metreSelect" class="metre" required>
    <option value="" disabled selected>Select number of metres</option>
    <option value="one">One</option> 
    <option value="two">Two</option> 
</select>

JavaScript

$("#metreSelect").change(function(){
	saveSettings($(this).val());
});

function loadSettings() {
	if(localStorage.getItem("selectedMetre")){
    $("#metreSelect").val(localStorage.getItem("selectedMetre"));
	}
}

function saveSettings(val) {
	localStorage.setItem("selectedMetre",val );
}