There is no term to how long you can factor with DSA. We have clients who have been factoring with us for over 20 years, and they've never had to sign another contract from when they first started up with us. We also have no minimum term, so you can stop factoring at any time and since factoring isn't a loan, you have nothing to pay back.
A small business loan from a bank comes with a term. When that term is up you have to pay back the loan along with all interest that has accumulated on it. If you don't have the money you'll have to make sure that you secure another bank loan before the current loan's term is up.