If I sell someone an item (e.g. an orange), and I attach a condition (e.g. "you may not make orange juice"), is it successfully binding? What happens if that someone does violate the condition (e.g. makes orange juice)?
The concept is the subject of interesting debate between the authorities, particularly nowadays in the realm of intellectual property. There's a good writeup of some important sources on pages 19-24 of this YU Shavuot-To-Go packet by R' Josh Flug.