Change expiration date on programmatically created Woo Commerce Subscription

I am creating a functionality for my client to offer subscription as a gift,

the last thing I need to do is to affect a subscription to a user.

I have succeeded, but since the user buys the subscription with a certain duration, I need to have an expiration date.

But when I use the built-in function “update dates” only the next payment gets affected

$product = wc_get_product($formuleId);
    $order->add_product( $product, 1 );
         
$dt = new DateTime('now');
  $dayNumber1 = date_format($dt, 'd');
    $dayNumber1 =   intval($dayNumber1);
  $dayNumber = $dayNumber1-14;
  $dayNumber *= -1;
$dt->modify($dayNumber.' days');

$startDate = $dt->format('Y-m-d H:i:s');
if($dayNumber1<=14){
    $nbrMois = $row->NbrMois-1;
} else {
    $nbrMois = $row->NbrMois;
}


$dt->modify('+'.$nbrMois.' month');

$endDate = $dt->format('Y-m-d H:i:s');

         
    $sub = wcs_create_subscription(array(
        'order_id' => $order->get_id(),
        'status' => 'pending', // Status should be initially set to pending to match how normal checkout process goes
        'billing_period' => WC_Subscriptions_Product::get_period( $product ),
        'billing_interval' => WC_Subscriptions_Product::get_interval( $product )
    ));

    if( is_wp_error( $sub ) ){
        return false;
    }

    // Modeled after WC_Subscriptions_Cart::calculate_subscription_totals()

         

 
    // Add product to subscription
    $sub->add_product( $product, 1 );

  
    $dates = array(
        'trial_end'    => WC_Subscriptions_Product::get_trial_expiration_date( $product, $endDate ),
        'next_payment' => WC_Subscriptions_Product::get_first_renewal_payment_date( $product, $endDate ),
        'end'          => WC_Subscriptions_Product::get_expiration_date( $product, $endDate )
    );


    $sub->update_dates( $dates );