I have developed one windows application which has licensing to its users. I want to set validation for the product key in offline(Without internet connection). For Example, during Windows operating system installation, the product key will be validated and used to activate the operating system. Such that i want some idea about how to do this concept.
You can make a table or record of the product key and its license period. Ask to user for entering the product key, match the entered key through coding, if it matches then only allow for installation.