WooCommerce Subscriptions and LearnDash, based on the work of https://thomaslecoz.com/learndash-with-woocommerce-subscriptions/#code-update

functions.php

<?php

add_action('cancelled_subscription', 'remove_course_access', 10, 2);
add_action('subscription_put_on-hold', 'remove_course_access', 10, 2);
add_action('subscription_expired', 'remove_course_access', 10, 2);
add_action('activated_subscription', 'give_course_access', 10, 2);

function send_receipt($order_id){
	//if($new_status == 'processing' && $status != 'completed' || $new_status == 'completed' && $status == 'processing'){
	if($status != 'processing' && $status != 'completed') {
		$order = new WC_Order($order_id);
		$products = $order->get_items();

		foreach($products as $product){
			$courses_id = get_post_meta($product['product_id'], '_related_course', true);
			if($courses_id && is_array($courses_id)){
				foreach($courses_id as $cid) {
					$already_in = false;

					if(empty($order->customer_user) || empty($cid)) {
						error_log("[EMPTY] User id: " . $order->customer_user . " Course Id:" . $cid);
						return;
					}

					$meta = get_post_meta( $cid, '_sfwd-courses', true );
					$access_list = $meta['sfwd-courses_course_access_list'];
					error_log('Access List: ' .$access_list);

					if (!empty( $access_list )) {
						error_log("Access List not empty: " . $access_list);
						$access_list = explode(",", $access_list);
						foreach($access_list as $c) {
							if(trim($c) == $order->customer_user)
								$already_in = true;
						}
					}

					if (empty( $access_list ) || !$already_in) {
						error_log("Empty list or user doesn't have access yet");
						ld_update_course_access($order->customer_user, $cid, $remove = false);
						// If it's a subscription...
						if (WC_Subscriptions_Order::order_contains_subscription($order) || WC_Subscriptions_Renewal_Order::is_renewal( $order )) {
							error_log("Subscription (may be renewal) detected");
							if ($sub_key = WC_Subscriptions_Manager::get_subscription_key($order_id, $product['product_id'])) {
								error_log("Subscription key: " . $sub_key);
								$subscription_r = WC_Subscriptions_Manager::get_subscription( $sub_key );
								$start_date = $subscription_r['start_date'];
								error_log("Start Date:" . $start_date);
								update_user_meta($order->customer_user, "course_".$cid."_access_from", strtotime($start_date));
							}

						}
					}
				}
			}
		}
	}
}

function remove_course_access( $user_id, $subscription_key ) {
		
	// Get the course ID related to the subscription
	$subscription = WC_Subscriptions_Manager::get_subscription( $subscription_key );
	$courses_id = get_post_meta($subscription['product_id'], '_related_course', true);

	// Update access to the courses
	if ($courses_id && is_array($courses_id)) {
		foreach ($courses_id as $course_id) {
			ld_update_course_access($user_id, $course_id, $remove = true);
		}
		
	}
}
	
function give_course_access( $user_id, $subscription_key ) {

	// Get the course ID related to the subscription
	$subscription = WC_Subscriptions_Manager::get_subscription( $subscription_key );
	$courses_id = get_post_meta($subscription['product_id'], '_related_course', true);
	$start_date = $subscription['start_date'];
	error_log('Start Date :' . $start_date . ' Epoch: ' . strtotime($start_date));

	// Update access to the courses
	if ($courses_id && is_array($courses_id)) {
		foreach ($courses_id as $course_id) {
			
			error_log("Checking for course: " . $course_id . " and User: " . $user_id);
			// Check if user already has access
			$already_in = false;

			if(empty($user_id) || empty($course_id)) {
				error_log("User id: " . $user_id . " Course Id:" . $course_id);
				return;
			}

			$meta = get_post_meta( $course_id, '_sfwd-courses', true );
			$access_list = $meta['sfwd-courses_course_access_list'];
			error_log('Access List: ' .$access_list);

			if (!empty( $access_list )) {
				error_log("Access List not empty.");
				$access_list = explode(",", $access_list);
				foreach($access_list as $c) {
					if(trim($c) == $user_id) {
						error_log("User already in the list, setting flag.");
						$already_in = true;
					}
						
				}
			}

			if (empty( $access_list ) || !$already_in) {
				error_log("Empty list or user don't have access yet.");
				ld_update_course_access($user_id, $course_id, $remove = false);
				// Replace start date to keep the drip feeding working
				error_log("Updating subscription date to original order");
				update_user_meta($user_id, "course_".$course_id."_access_from", strtotime($start_date));
			} 
		}
		
	}
}