Is there a plan to make a "Save" button anytime in the future?

The problem with creating a "Save" button would be that the data needs to be saved somewhere.  There are a couple ways to allow for users to save their current data and continue where they left off. 

The easiest way is to allow for partial submissions and give users and edit submission link in the confirmation email:

https://www.jotform.com/help/40-How-to-Let-Users-Update-Their-Form-Submissions-at-a-Later-Date

Users would be able to submit the form and return to their specific submission at a later date to finish completing it.

The second way is a bit more complex and requires specific form setup:

https://www.jotform.com/help/97-How-to-Save-Forms-and-Continue-Later

This method stores the form data in the users session data.  The drawback to this is they would need to use the same device they began the form with to complete it.