I have a samsung note 2 but I have a problem 1GB ram is always used even if I don't use any app and that drain his battery he have 4.3 android (I tried update but I can't find new one) is this normal ?
Do you find any lag when opening applications or does it slow down when multitasking?
If no is your answer then it is a very normal behaviour.
My phone has 1 GB of RAM but more than 600 MB is always occupied and it doesn't lag anytime. You can read about RAM management in Android in so many developer forums if you'd like to.