Disallow suspending a subscription based on product ID

prevent_suspension_per_product.php

function prevent_suspension_per_product( $user_can_suspend, $subscription ) {
  if ( ! $user_can_suspend ) {
      return $user_can_suspend;
  }

  $product_ids = array(438,128,2,345); // Change to whatever product ids you want to prevent suspension for

  foreach ( $product_ids as $product_id ) {
    if ( $subscription->has_product( $product_id ) ) {
      $user_can_suspend = false;
      break;
    }
  }
  return $user_can_suspend;
}
add_filter( 'wcs_can_user_put_subscription_on_hold', 'prevent_suspension_per_product', 15, 2 );