problems with canceling free trial

I subscribed to a premium free trial. So far so good. Terms and conditions states that if you don't cancel the free trial before it ends, they will charge you. In my case the trial ends on august 5. I decide to cancel today, one day before the trial ends.

Google play sends me an email stating my trial will be canceled exactly on august 5, when billing occurs.

Since the trial is canceled exactly when they would charge me, is there a possibility that they will charge me even if I ordered a cancelation?

I also downgraded my account in the chess.com website and cancelled automatic payment. I don't know if that's enough to stop any charges.

I REALLY REALLY CAN'T AFFORD TO LOOSE THAT MONEY ON MY ACCOUNT. It's not even enough to pay a yearly premium membership, and I need that money to pay groceries and services.