I’m not an expert in this field yet!, but it seems to me there could be some type of code or password that would differentiate the source. For example, it might be something as simple as “coffee” for coffee sleeves, “coaster” for bar coasters, or “flyer” for printed flyers, as well as “online”, obviously for online. The sign-in/login page for the app could say something like, “Enter code for special offer!”