gform_stripe_customer_id

add_filter( 'gform_stripe_customer_id', 'get_stripe_customer_id' );
function get_stripe_customer_id( $customer_id ) {
	if ( is_user_logged_in() ) {
		$user_id = get_current_user_id();
		$customer_id = get_user_meta( $user_id, '_stripe_customer_id', true );
		gf_stripe()->log_debug( __METHOD__ . "(): Retrieved Stripe Customer ID {$customer_id} from WP user ID {$user_id}" );
	}

	return $customer_id;
}

add_filter( 'gform_stripe_customer_id', function ( $customer_id, $feed, $entry, $form ) {

	$feed_name = rgars( $feed, 'meta/feedName' );

	gf_stripe()->log_debug( 'gform_stripe_customer_id: Running for Feed: ' . $feed_name );

	// Define the names of the feeds you want this code to run.
	$feed_names = array( 'feed name one', 'feed name two' );

	// Abort if the entry was processed by a different feed or it's not a product and services feed.
	if ( rgars( $feed, 'meta/transactionType' ) !== 'product' && ! in_array( $feed_name, $feed_names ) ) {
		return $customer_id;
	}

	if ( empty( $customer_id ) ) {
		$response = gf_stripe()->get_stripe_js_response();
		if ( ! empty( $response->id ) && substr( $response->id, 0, 3 ) === 'pi_' ) {
			try {
				$intent = \Stripe\PaymentIntent::retrieve( $response->id );
				if ( ! empty( $intent->customer ) ) {
					gf_stripe()->log_debug( 'gform_stripe_customer_id: PaymentIntent already has customer; ' . print_r( $intent->customer, true ) );

					return is_object( $intent->customer ) ? $intent->customer->id : $intent->customer;
				}
			} catch ( \Exception $e ) {
				gf_stripe()->log_debug( 'gform_stripe_customer_id: unable to get PaymentIntent; ' . $e->getMessage() );
			}
		}

		$customer_params = array();

		$email_field = rgars( $feed, 'meta/receipt_field' );
		if ( ! empty( $email_field ) && strtolower( $email_field ) !== 'do not send receipt' ) {
			$customer_params['email'] = gf_stripe()->get_field_value( $form, $entry, $email_field );
		}

		// Optional - Customer name using a Name field that has id 8. Update the id number or remove the following line.
		$customer_params['name'] = rgar( $entry, '8.3' ) . ' ' . rgar( $entry, '8.6' );
		gf_stripe()->log_debug( __METHOD__ . '(): Name: ' . $customer_params['name'] );

		// Optional - Customer phone using a Phone field that has id 5. Update the id number or remove the following line.
		$customer_params['phone'] = rgar( $entry, '5' );
		gf_stripe()->log_debug( __METHOD__ . '(): Phone: ' . $customer_params['phone'] );

		$customer    = gf_stripe()->create_customer( $customer_params, $feed, $entry, $form );
		$customer_id = $customer->id;
		gf_stripe()->log_debug( 'gform_stripe_customer_id: Returning Customer ID: ' . $customer_id );
	}

	return $customer_id;

}, 10, 4 );