When registering iLok-protected software, your iLok User ID is required so that a license can be deposited in your iLok account.
If you do not know what your iLok User ID is, you should go to iLok.com and verify that you have the correct User ID.
If you have not previously created a user account at iLok.com, you will need to do that first in order to get your User ID. You can go here if you have forgotten your iLok User ID.
It is displayed in the top left corner of iLok License Manager: