For the game: The Two Thrones, the code is inside the Ubisoft box.
For my PC version, the code is on a label above the CDroms.
If you are missing such a key, maybe the following will help you:
Answer ID 10810
Missing Install Key.
I am trying to install Prince of Persia: The Two Thrones, and it is asking me for an install key. I do not see an install key in the box. How can I install this game?
The Install Key for Prince of Persia: The Two Thrones is: BZ7A9-X488N-725MY-E9FND-TLPDZ
Please note, this key code is only used for the installation of the game.</span>
Are you playing on a Windows Vista or Windows 7 or Windows 8 beta ... or on what platform are you playing?
POP T2T came with a stupid "hidden at the time" root kit known as StarForce to protect their software from being pirated.
POP T2t was only written for Windows 2000/Windows XP and tested only for a single cpu computer processor.
You need to check various postings in the Community Technical Forum how to
- download and install some sort of work-around for StarForce to work on Windows Vista/7/8 etc.
- how to run the game "as an administrator" targeting one of the cpus on your probable multi-cpu computer.
I still run my Windows XP 800 MHz computer that I built in the year 2000 for POP Sands of Time,
so I have yet to encounter such problems.