public function begin( \Aimeos\MShop\Subscription\Item\Iface $subscription )
	{
		if( empty( $this->groupIds ) ) {
			return;
		}

		$context = $this->getContext();

		$manager = \Aimeos\MShop::create( $context, 'customer' );
		$baseManager = \Aimeos\MShop::create( $context, 'order/base' );

		$baseItem = $baseManager->getItem( $subscription->getOrderBaseId() );
		$item = $manager->getItem( $baseItem->getCustomerId(), ['customer/group'] );

		$item->setGroups( array_unique( array_merge( $item->getGroups(), $this->groupIds ) ) );
		$manager->saveItem( $item );
	}