Car Alarms: Pathfinder alarm, alarmtek, dash area

Question
I recently purchased a '98 Nissan Pathfinder.  I received two keys, but no "keyless" button.  Now, whether I lock the car with the key or the button inside the driver's door, the alarm will sound within a few minutes or a few hours.  How can I either reset or bypass this system?

Answer
Make, model & year of the vehicle?

Please be more descriptive if possible.

"GOING OFF?"

I need to determine whether it's a factory alarm
issue or, if it's an aftermarket system you are
dealing with.

Is it: Headlights flashing, car horn honking
and a worded SECURITY" light in the dash flashing?
(doubtfull since none of the notes show this
car as having a factory alarm system)=FACTORY

Or,

is it: flashing parking lights,
an LED in the dash area, and a siren
going off?= AFTER MARKET

Let me know more on this to better
advise you on a course of action
to take.

Best Regards,

Robert Martin
CEO/ALARMTEK
CARALARMMAN.com