Here is informative content regarding , including what they are, how they work, legitimate sources, and important warnings about unauthorized keys. What Is a Rosetta Stone Activation Key? A Rosetta Stone activation key (also called a license code or product key) is a unique alphanumeric string used to unlock and register the Rosetta Stone language learning software. The key verifies that you have a legitimate license to use the product, whether it’s a downloadable version, a CD/DVD copy, or a subscription.