I would assume the "Save and Resume later" function is what you're after. Ifr you don't see that under the Form Properties, you're probably using MF that is an older version.
On your form, go to the Form Properties > Processing Options > and check the box "Allow Clients to save and resume later."
Note this option will work on a form with two or more pages i.e. a form with at least one "Page Break".
Note, unsubmitted forms will appear in the form entries list, but you have to filter on "unsbmitted" or something similar to see the entries - you can do as you can with submitted entries, actually open the form and submit it yourself, or otherwise leave it for the original user to do.
The intention is for the front-end user to save the form and come back at a later time to submit it.