Maybe they made the pact with the patron for the power , but the patron cannot simply take the power away ? This is how I tend to view them whatever deal was struck , it ' s done . If a warlock wants more power perhaps they do more for their patron , or perhaps whatever power they ' ve been given simply grows over time in the same way a bard ' s or sorcerer ' s does . I think a patron could theoretically try to take back whatever they gave them but would have to be annoyedangry enough and even then it would take some effort on their part . Not just a snap of the fingers and the warlock is depowered . Ultimately I think pacts are purposefully left vague so that each individual playerDM can decide the nature of why and how a pact works .