Predict if user will come the next day or not
I think that you should stop thinking about modeling and instead start thinking about the meta datasets that you can draw from what you already have. I have also downvoted the previous answer you received because it's making the same mistake. 

One of the most consistent mistakes I see in data science (by all levels of scientists) is that they skip the data transform/wrangling stage and just go straight into modeling. That's a MASSIVE mistake and the answer you seek starts well within this stage. 

So, I want you to take a step back and think about your data. What do you need to know about a user? What are some of the features of each user? What are the features of when they visited? What day? What time? Was it the morning or the afternoon? How many days in a row was it? What is the gender of the user? And so on and so on. 

Your goal is to create a dataset that has one line per user and the same features for all users. From there, you'll be in a better position to make better decisions about modeling and anything else you want to know about your data.