No, because this isn't a Phillip K Dick novel. Police don't do pre-crime: they comes after the crime happened. We are also not the police. You needn't ask you

No, because this isn't a Phillip K Dick novel. Police don't do pre-crime: they comes after the crime happened. We are also not the police. You needn't ask your customers "Are you going to do something bad?" (sometimes regulation forces you to ask if they _did_, but that's a past-looking question). But once you know they are using that service for unacceptable activities, it's ok to remind them that such behavior is unacceptable. After all, you don't want having a reputation of the place that has those kind of customers.