QR Code Generator Pro does not integrate any ads, neither into the QR Codes created through our system nor into the user interface of our software. This is completely independent of your account being in the trial period or subscribed to a plan.
If you see any ads when scanning QR Codes, they're from the scanner app(s) that you have downloaded on your device.
Free apps are often financed through in-app advertising. If you want to stop seeing ads, you need to download a different (ad-free) scanner app.