How do I build a model to predict which service a customer will use on an app? There's an app with over 50 services. I have the data on the type of service a specific customer (they have a unique customer number) does on the app, the date, location, time, duration on a service and the volume of that service. 
I want to build a ML model to personalize the services the customer gets daily when they open the app. i.e. Top 6 services they're likely to use for that day
Which machine learning technique would be optimal to achieving this?
Start with the most frequent used ones... then explore the need to build a more complex model. Chances are the distribution of service is skewed and you don’t really need to build a model outside a top n.