A license activation key validates and activates purchased software. Sometimes called a product key, a license activation code may be found printed on the CD sleeve, somewhere on the back of the package, or, for software purchased online, may be sent to the consumer in an email.
A license activation key is usually a series of numbers and letters that is unique to every piece of software. Product keys can be any length and help software developers to know that a customer has purchased software legally. Product keys for software that will be running on several machines may need to be obtained directly from the vendor.