The "string" manifests in two distinct ways depending on the licensing model:
Modern Wibu keys are designed to prevent cloning. If an operating system detects a spoofed dongle (common in piracy attempts), BioNumerics will often detect the anomaly and refuse to launch, throwing a "Security violation" error.
IT administrators frequently encounter issues where the software claims the license string is "invalid" or "not found."
Think of the dongle (hardware key) as the key, and the license string as the lock’s combination. You plug the dongle into a USB port, but the software asks for the string to confirm that the specific dongle you are using has the permissions you need.