Each QR frame of a template consumes 1 credit at generation: a piece with two QR frames costs 2 credits per contact.

Consumption is measured by the sum of the credit events for the current period for the workspace. The remaining balance = plan cap − consumed (+ any bonus credits).

The period follows the Stripe subscription (persisted dates, robust to a missed webhook); with no subscription, it falls back to the calendar month (UTC).

If a batch exceeds the remaining balance, QR Queen first draws from perpetual bonus credits ("CreditBonus", coming for example from Stripe coupons) before refusing the operation with the error "CREDIT_LIMIT_EXCEEDED." Bonus credits are consumed oldest first (FIFO).

Spending is recorded in a serializable transaction with retries: several simultaneous generations on the same workspace cannot cross the cap twice.