MikroTik RB750 Caps

Is it possible to have a bandwidth manager in this product (MikroTik RB750)? I have a wireless network and would like to limit users to 2GB after which i slow them down.

Use a Hotspot.
http://wiki.mikrotik.com/wiki/Manual:IP/Hotspot/User

limit-bytes-in (integer; Default: 0)	Maximal amount of bytes that can be received from the user. User is disconnected from HotSpot after the limit is reached.
limit-bytes-out (integer; Default: 0)	Maximal amount of bytes that can be transmitted from the user. User is disconnected from HotSpot after the limit is reached.
limit-bytes-total (integer; Default: 0)	(limit-bytes-in+limit-bytes-out). User is disconnected from HotSpot after the limit is reached.

The 750 comes with a license that can do 200 Hotspot users.

Can i do it per user? so based on ip address or mac? Also can i set this using the GUI?

The cap is shared for that user account, so if each unique user on the network uses a different username and password, they each get a separate cap.

Anything you can set on the CLI you can set in the GUI. They are equivalent. “/ip hotspot user” in the CLI in the GUI is reached by clicking on the IP button to fan out the menu, select Hotspot, then the User tab.