Activate
When your DAW tries to open the plug-in, you get the following message. Press Try to continue.

Log in
Log in to your iLok account using your iLok User ID.

Select a Location
In most cases you'd put the trial licence on your computer, but in case you have an iLok USB Smart Key, you can put it there.

Success!
The plug-in is now ready for use.

Expiration Warning
Now and then you might get an expiartion warning to make sure you know when the trial runs out.