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]
(..) Chances are, we go home, they'll court martial us. Yeah, there's that. And for the rest of you guys... I guarantee they will never send you back up here again. Good. So, if we go for it, how would it work? I plot the course and execute it. (..)2015 The Martian