A fake key file will lock you out of the ARRC (Anno 2070’s online world council), co-op mode, and future updates. Given that the Deep Ocean expansion is essential for the full experience, you’d be stuck with a broken, outdated version.
Those instructions are almost always for cracked versions of the game. They replace the DRM check with a fake one. This is piracy and comes with the risks mentioned in Part 3. Anno 2070 Serial Number Key File
Sometimes yes, but only if you first deactivate the key on the old computer (if TAGES was used) or log out of Ubisoft Connect. Then copy license.ubisoft to the same folder path on the new PC while offline. However, this fails more often than it succeeds. Safer to simply re-enter your key online. A fake key file will lock you out