Darius hums for a moment "Both your students and the villagers should be able to decide if they want to give the demon back at any given time." He offers for a start, and then pauses for a while "And you should include a clause for what happens if one of your students decides they want to keep a demon, especially in the case that the villager may want it back. But I think that the minimum trial period should be a month, so that everyone has time to accommodate the change before deciding it's different and not for them in the first 10 minutes."