Best answer by stephenrand
As this is your first post, welcome to the Pure Planet community!
Your balance goes up when your direct debit is paid, and goes down when your monthly usage is priced and deducted. That should happen on the monthly anniversary of when you started with PP - sometimes a weekend or bank holiday delays the direct debit payment and it doesn't appear on your monthly statement - until the next month. But you can check your balance any time on the app.
Your monthly meter readings help to keep your usage figures accurate and on track.
Hope that helps