Which cookie type is being used in the "loose check" option?

When using "loose check" is the cookie being used a "Session Cookie" (cleared when the browser is closed and reopened) or "Persistent Cookie"? If it's Persistent does it expire? When?

As far as I can tell it is using a "Persistent / Permanent Cookie" since even if you close the web browser you will not be able to re-submit the form once you have submitted it once, about the expiration, it will be stored in the web browser until the web browser is deleted, as far as I know there is not expiration date.

Here's a screen-cast about what I can see on my test: 

So once the form has been submitted in one web browser it cannot be submitted again until the web browser data is cleared or the feature is disabled on the form. 

Please if you have any question, let us know.