dealing with codeigniter date helper

[eluser]basty_dread[/eluser]
Hello Guys. i'm here again to ask for your favor, strategies about my problem with date

this is what i want to do:

I have a registration form when this user click the register button
the system saves all the information that has been entered.

my question is,

how can i save the current date and time of the user on his or her timezone?

plus his/her account is limited, how can i add let say 6 months and save to the database the expiration of his/her account.


i hope you guys can help me..
thank you very much.