There is no safe, working "Activation Code For Epic Pen" available on the dark corners of the internet.

Epic Pen Activation Code is the unique key required to unlock the "Pro" version of this popular screen annotation software. While a basic version is available for free, entering a valid code transforms the tool from a simple pen into a professional presentation suite. How to Obtain a Code

Same as Steam. If you buy the "Pro" add-on inside the Microsoft Store app, the store tells the app, "This user owns Pro." Done.