Necessary for audio software these days as an anti-piracy method. Need this to be plugged in while the software is in use. It is a bit buggy to use as the iLok remains undetected on insert until you move it around in the port till it works. You need to download the iLok software to manage your software licenses.
This thing is a glorified pen drive, except it can't be hacked and it's a bloody monopoly. Had to buy this because I lose the one I got with Pro Tools.