Dynamic QR Codes need an ongoing subscription in order to remain active. After the completion of 14-days Free Trial, Dynamic QR Codes will deactivate and won't work on scanning unless subscription is started. See plans and pricing.
Dynamic QR Codes generated during Free Trial gets saved in your Scanova account and becomes active as soon as you start the subscription. You can view the QR Codes in Saved QR Codes section in your account.
To sum up, you can use the same QR Code which you created during your Free Trial after you start a subscription.