WordPress/Woocommerce Sessions

Solution:

Your cart should be clearing after checkout so something else may be wrong.

You could create a function with empty_cart() in it that is triggered when payment is complete “just in case”. See: http://docs.woothemes.com/wc-apidocs/class-WC_Cart.html

add_filter( 'woocommerce_payment_complete_order_status', 'pg_woocommerce_payment_complete_order_status', 10, 2 );
function pg_woocommerce_payment_complete_order_status ( $order_status, $order_id ) {

    $global $woocommerce;
    $woocommerce->cart->empty_cart();

}