I’m using the latest version of the stripe API. I have a shopping cart where people can pay instantly with a credit card or generate a bill and pay later. What type of ID should I save in the database so that if the customer makes the payment by bank slip and the bill is paid, upon receiving the command via the webhook I can identify who made the payment.

This is because when the order is made, some ID needs to be registered in the DB, in this example I am calling it IDx:

$checkout_session = $stripe->checkout->sessions->create([
  'customer_email' => '[email protected]',
  'metadata'    => [
    'pedido_id' => "ABC123", //Id do pedido
  ],
  'line_items'   => [
    [
      'price_data' => [
        'currency'   => 'brl',
        'product_data' => [
          'name' => 'T-shirt',
        ],
        'unit_amount' => 2007,
      ],
      'quantity'  => 1,
    ]
  ],
  'mode'      => 'payment',
  'success_url'  => SISTEMA['painel'] . '/app/Modules/pagamentos/stripe/sucesso.php',
  'cancel_url'   => SISTEMA['painel'] . '/app/Modules/pagamentos/stripe/cancelado.php',
]);


$rs = $mysqli->prepare("INSERT INTO financeiro_logs (IDx, retorno_webhook) VALUES (?,?) ");
$rs->bind_param('ss', $IDx, $checkout_session);
$rs->execute();

header("HTTP/1.1 303 See Other");
header("Location: " . $checkout_session->url);

Links de referencia para seu aprendizado:

• https://docs.stripe.com/payments/boleto,
• https://docs.stripe.com/payments/boleto/accept-a-payment,
• https://docs.stripe.com/payments/checkout/fulfill-orders