I didn't read the link you provided ... having said that ... you could create a small text file with a "key" - place that text file somewhere on the computer's hard drive and name the file something that doesn't reflect back to your
add-in. Example : If your add in is called "Press Button To Copy Files To Selected Folder" .... name the small text file something like "300487GDH.txt"

Then in your Add In have it check the existence of that small text file first before running. If the text file isn't there, advise your user they are not licensed for its use.


Creating a KEY in the system registry is not that difficult. This is another possibility, where your Add In will check the registry first for the required key.