Update using-predictions.md

Author: samkcrespo

src/unify/Traits/predictions/using-predictions.md

@@ -108,6 +108,8 @@ Every seven days.
 
 You get five predictions as part of Engage Foundations or Unify Plus. To purchase more predictions, reach out to your CSM.
 
+Predictive Audiences contribute to the Engage limit of 100 audiences. Regardless of whether an audience is manually crafted or generated via predictive modeling, each one is counted as a single audience within this limit.
+
 #### Is Predictions HIPAA-compliant?
 
 No, Predictions isn't HIPAA-compliant. Avoid using Predictions for health and life science applications.