This isn't a bug in your copy of the game. It’s a . Apache: Air Assault uses an old online Digital Rights Management (DRM) system. When you enter your activation key, the game tries to phone home to a verification server. The problem? Those servers were likely deactivated years ago.
Telemetry & Security
To fix the "Checking activation code, please wait" hang in Apache: Air Assault This isn't a bug in your copy of the game
Search for the latest standalone Yuplay or Gaijin.net agent. This isn't a bug in your copy of the game