The software comes with a 'money-back guarantee'. [=a promise that the money you spend on a product will be returned if the product is not good enough]
We used our house as a 'guarantee' for the loan. [=we said that the bank could take our house if we did not pay back the loan]
There is no 'guarantee' that they will approve the contract. [=there is no way to be sure that they will approve it]
(..) I need you to take control of Wayne Enterprises... and this reactor. - To do what with it? - Nothing. Until we can guarantee its safety. - And if we can't? - Decommission it. Flood it. Destroy the world's best chance for a sustainable future? If the world's not ready, yes. (..)2012 The Dark Knight Rises