Know who submits the form

Good morning everyone,
assuming that a great job is being done with this plugin and soon we will move to the Pro version, now I have a need to manage:
I have a site with a Private Area and some modules are the same inserted in the various areas.
Since the forms will only be used by registered users but I don’t want to create a single form for each user,
how can i find out who sent the form? I saw that there is the option for the IP address, but it is not immediately identifying and then some tables will be public, I don’t want to show the IP.

Thank you very much