A pocket is where you usually store coins, wallet, keys and perhaps (in chest pockets) a small cell phone or walkman. It is part of clothing and so items (which we call worn devices) in pockets must be transferred to other clothing when you change. This suggests that separate devices for Consumerium Services are a bad idea as they might get left in the other pants or jacket. Although a key chain may work as few people leave the house without their keys.
Taking something out of a pocket to use it, using it, and then putting it back in, is inconvenient enough that if someone has a choice to avoid doing so, they usually do avoid it. The Consumerium buying signal should be accessed with no need to fish in pockets.