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function ml_add_rcp_customer_membership( $user_id, $feed, $entry ) {

	if ( empty( $user_id ) ) {
		return;
	}

	/**
	 * We can either get a form field value,
	 * or hard code the level
	 */
	// $rcp_level = 1;
	$rcp_level = rgar( $entry, '2' );

	/**
	 * Create RCP customer
	 * https://docs.restrictcontentpro.com/article/2105-rcp-add-customer
	 */
	$customer_id = rcp_add_customer( array(
		'user_id' => $user_id,
	) );

	/**
	 * Create RCP membership
	 * https://docs.restrictcontentpro.com/article/2082-rcp-add-membership
	 */
	$membership_id = rcp_add_membership( [
			'customer_id' => $customer_id,
			'object_id'   => $rcp_level
		]
	);

}

add_action( 'gform_user_registered', 'ml_add_rcp_customer_membership', 10, 3 );