There are two ways to find your forgotten ULBID: 

1. You can connect to My ULB with your recovery email address and your password:
You will then find your ULBID, once logged in, in the upper right corner next to your first and last name. 

2. You don't know how to connect to MyULB:
Reset your password through the page: I have forgotten my ULB password. How to recover it? 
You will be reminded of your ULBID in the password reset email.