In my case, I bought both games (SH 1.4 and u-boat missions) from an online purchase/download site, which provided me with the keys. Then, after installing, I had to connect to Ubisoft's server and they asked me the key. Once punched in, the game worked fine.
If you but it on a hard copy, same thing: first time you run the game, the game automaticaly connects to Ubisot's servers and ask you for the key.
It's the same procedure everytime you install/reinstall the game.
The server may be offline so you may have to try it again some other time. It happened to me once. Wait till tomorrow and try again.
It's funny, you shouldn't be having this problem, but every once in a while someone complains about the very same thing. Hum...
