Because was originally distributed as a digital trial (often found on sites like Uptodown or Softonic ), players are frequently asked for an activation code or "Unlock Key" to play beyond the trial period.
: The game launcher often mixed the product key with a unique "Hardware ID" from the user's PC. Namco All Stars Pac Man Activation Code
Visit the GOG Redeem page, log in, and enter your code. Because was originally distributed as a digital trial