As you know number of Nintex workflow and Nintex form are limited by the licensing on O365.
My problem was, I have many sites and lists, Its hard for me to find which list using the Nintex workflow and Nintex form.
May I know its that any easy way to do so?
There is no way to get that information right now. Maybe through Nintex Support somehow.
However in the next weeks new Hawkeye Inventory Lenses (Advance Preview: Nintex Hawkeye Inventory Lens ) are going GA, so that this tool will deliver you a very precise information regarding where do you have what.
So stay tuned and wait for it. One important thing is - this is going to be available only for Enterprise license. In case you have Standard then... Try contacting Nintex Support