WordPress at a glance
function is not described

wc_update_new_customer_past_orders() WC 1.0

Get past orders (by email) and update them.

Return

Int. Nothing.

Usage

wc_update_new_customer_past_orders( $customer_id );
$customer_id(int) (required)
Customer ID.

Code of wc_update_new_customer_past_orders() WC 5.3.0

<?php
function wc_update_new_customer_past_orders( $customer_id ) {
	$linked          = 0;
	$complete        = 0;
	$customer        = get_user_by( 'id', absint( $customer_id ) );
	$customer_orders = wc_get_orders(
		array(
			'limit'    => -1,
			'customer' => array( array( 0, $customer->user_email ) ),
			'return'   => 'ids',
		)
	);

	if ( ! empty( $customer_orders ) ) {
		foreach ( $customer_orders as $order_id ) {
			$order = wc_get_order( $order_id );
			if ( ! $order ) {
				continue;
			}

			$order->set_customer_id( $customer->ID );
			$order->save();

			if ( $order->has_downloadable_item() ) {
				$data_store = WC_Data_Store::load( 'customer-download' );
				$data_store->delete_by_order_id( $order->get_id() );
				wc_downloadable_product_permissions( $order->get_id(), true );
			}

			do_action( 'woocommerce_update_new_customer_past_order', $order_id, $customer );

			if ( get_post_status( $order_id ) === 'wc-completed' ) {
				$complete++;
			}

			$linked++;
		}
	}

	if ( $complete ) {
		update_user_meta( $customer_id, 'paying_customer', 1 );
		update_user_meta( $customer_id, '_order_count', '' );
		update_user_meta( $customer_id, '_money_spent', '' );
		delete_user_meta( $customer_id, '_last_order' );
	}

	return $linked;
}