Thanks for all the replies.

Appreciated.
Further questions:
I now own the apartment in Copper Building on Treasure Island City. The control console has the [RESTRICT ACCESS] button already toggled on.
* What exactly does this button do?
The tooltip states:
"Unrestrict Estate Access, after which estate cannot be traded."
My apartment is currently is set to PUBLIC - and Restricted Access entry states: Yes.
* What exactly does this mean?
* Can I untoggle [RESTRICT ACCESS] button later? Or is it locked forever once I click it?
* If so, do I get a warning prompt in case I accidently click it?
* And if I do click it - do I lose my "Deed" and never be able to trade it later (In case I need to barter for better place/etc)?
Thanks again.