Once you exchange your serial number for a Steam key , your original serial number is permanently blocked and cannot be used again.
If you lost your serial number, email support@citycardriving.com with your order ID and payment details. City Car Driving Product Key And Serial Number
The standard license allows one active installation per key. If you install on a second PC, the first one will be deactivated. For multiple computers, you must buy additional licenses or use Steam Family Sharing. Once you exchange your serial number for a