The purpose of an activation key is to prevent software piracy by ensuring only users who have purchased a program can use it. Some software programs will not function without a valid activation key, while other programs will run in "trial mode" or with restricted functionality. Registering or activating the software with the activation key removes these limitations.
There is no standard activation key format, but most include both letters and numbers. They often contain groups of characters separated by dashes for readability. Most license keys contain at least 10 characters, and some may have over 30. Below is an example of a typical activation key:
Developers can implement software activation keys in several different ways. The most basic method is to simply check a key against a database or list of keys. If a user enters an activation key that matches one in the list, the software is successfully activated. A more advanced method is to generate activation keys dynamically based on a user's registration information (such as an email address). An algorithm in the program can then check the key to see if it corresponds with the email address used to register the software program. Modern software programs often use online activation, which verifies the key on a remote server. This allows the developer to limit the number of uses for each key and revoke keys if necessary.
Software activation keys may be found inside retail software boxes or order confirmation emails. You can typically open the activation window in a software program by locating the "Activate" or "Register" option in the program.
NOTE: An activation key may also be called a product key, software key, license key, registration code, or serial number.