If an unauthorised user is found to be using the software, the legitimate user can be identified from the code. The vast majority of possible codes are rejected by the software. The software will function only if a potential user enters a valid product code. A software serial number, otherwise called a product key, is usually not embedded in the software, but is assigned to a specific user with a right to use the software. The purpose and application is different. Serial numbers may be used to identify individual physical or intangible objects (for example computer software or the right to play an online multiplayer game).

This practice by manufacturers limits the right to repair electronic devices. This is queried by the software for proper release for use. This gives unique individual parts such as the screen, battery, chip and camera a separate serial number. In smartphones, serial numbers are extended to the integrated components in addition to the electronic device as a whole, also known as serialization.

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