No proof of payment...

When I first downloaded and installed SH4 via STEAM, I got a code that I had to write down and keep as I would need it next time.

What seems? Every time the computer is restarted, and I start SH4, I get another code that starts SH4 again.

Actually I don't have any proof of purchase!
I have to judge if STEAM recognizes me, then it is fine, but if STEAM does not recognize me, I can never prove that I bought a copy of SH4 + Missions from them, then I have a problem!

What do you think?

easy