Hi:
If you are taking SAS Academy for Data Science classes, in order to answer your question, we need to know what module you are working in (Big Data Module 1 or Module 2? Advanced Analytics Module 3, or 4 or 5?) Then, within the module, what class you're working in. If you are referring to a specific lecture or practice it is also useful to know what lecture or practice you're working on.
If you are NOT taking SAS Academy for Data Science classes and you just have a general question about Lift or Net Lift, then it might be useful to understand more about your data and what definition you are referencing -- is it a reference in the SAS documentation? is it a reference in a paper? in a textbook?
Without more information, it's hard for people to respond.
Cynthia