for example users consumption API that I mention it is connected to a billing system that this purchase con solution so if you can query data from billing then put in cash or even a long term cash because you see that this data won't be changed regularly for example we have a say is containing god bills to baby so if you once query the pay bill you know the amount you know when it was paid you can put it in cash if user comes inquiries he must to see his last 12 bills or some aggregations I don't know average bill amount buried for last