The product unit disclosed herein has identification data that are stored internally in memory. This stored identification data can be viewed as the product unit's “digital nameplate,” in that the data can represent the product unit's identifier, brand, and so on. Each data set is digitally signed while on the production line by using an encryption technique. The digitally signed data set is then written into the product unit's memory where it can be used for verification. A first digitally-signed data set can be used to control the use of one or more software modules that are provided by a software owner. The data that are undergoing signature contain at least one globally-unique identifier, which can be used to identify cloning attempts. Additionally, more than one digital signature can be used, in order to protect and control the use of features other than the software, such as the product brand.