John purchases a large rural property. He decides to build a number of cabins on the property but needs to clear the land first. John hires Peter to pick up rocks from his land and remove them.Peter asked John if once removed, he can keep the rocks and sell them to other people. John doesn't care and agrees. What legal arrangement allows Peter to enter the land for this purpose?

reference to: Bare license instead of profits of prendre.

- explain why this is?