In your Pickware account, you can manage which iOS devices are connected to your Pickware Admin. One device can be connected per booked license of WMS or POS.
If you get a message saying no free licenses are available when setting up a new iOS device, you can view the devices connected to your shop in your Pickware account under Shop → POS or WMS, under the entry Device Management, and remove them if needed to make room for new devices.