How to identify potential customers who are ready to convert in to paid?
Two items come to mind:


You will gain the most benefit from this site when you propose a model and let other people comment on and modify the model. As it stands, you are merely proposing what your data looks like. Do you have a model that you've tried? What data science steps have you already taken with your project? If you post that, this site will be of much better help to you
You should be aware that what you posted makes for a good initial dataset but that's all it is, your initial set. If I was in your position, I would be working towards developing a meta dataset that contains a much larger number of factors. When did the person join? What was the time in between actions? Which country is their IP address from? How many times have they logged into the tool? Etc, etc, etc. When you start to think of your data in this manner, and give yourself a much larger number of factors to start with, then you are taking steps that are much more likely to result in a reliable predictive model.