The best option is to use a database to store your player data. What database to use is ultimately in your court and what seems relevant based on your own research.
Inputting that data into a database should be easy for these two metrics simply because you're only talking about tracking the login date and timestamps of your players. Those timestamps will have to be stored every time they log into the game and when they log out.
Then simply put, you could query your player log data to return a result to Unity that displays in game as the TSQL query example below:
,DATEDIFF(MINUTES,[log-on-time],[log-off-time]) AS [Time Difference]
WHERE [player-id] = ...
Then this would result in the time difference between the log on time and log off time. Of course, if the user is currently playing, then you can alter the query to use GETDATE() functions depending on the RDBMS you are using to get the time difference between the log-on-time and the database server time for live players and ETC.
I would recommend this as opposed to trying to find a quick-fix or possibly licensing someone elses analytical reporting system. That's because you may find yourself wanting to store more data about your players that you also want to report on in-game as well out-of-game for your own personal metrics of the games progression.