I am not from Laminar Research; just a flight simmer from down under.
I am a little confused on what you have.
If your "dowmload" is recent why or where did you get XP10 from and why are you dabbling with XP10 instead of XP11. XP11 is a far better product and the latest version. If you recently downloaded from Laminar Research then your copy would be XP11. Not XP10. Version XP10.52 developed by Laminar ceased immediately after XP11 was released.
Firstly, a demo version from Laminar Research is free. If you have been "charged" or "had to pay" somebody else then you have been scammed. There is no product key required or made available but you are restricted to a time limit and a set location for a period of 10 minutes once you have setup your flight. When you purchase the full version of X-Plane from Laminar Research you will be provided with a product key and when applied to the demo version it will automatically open to the full version of X-Plane.
Laminar Research does not sell the steam version of X-Plane.
Secondly the information I have provided is of a generic nature as I do not support steam. If you do have a steam version then you need to read the following which has been taken from another posting.
- There are two versions of X-Plane. One version is steam and the other from Laminar Research.
- Because you are using the alternative version of X-Plane you are in the wrong forum. You need to ask a question in a forum specifically for your version.
- I do not use or support your version
- This forum is for the true official,genuine and original version of X-Plane developed by Laminar Research. Your version is a 3rd party modified or hybrid version that is taking a commercial advantage of the development work carried out by Laminar Research.
- There is no business connection between Laminar and your version.
- Your version installs differently to the Laminar version and only makes a final release version available to its users days after Laminar releases or updates to a newer version. Laminar makes beta versions available for public testing before an official release is made. I understand your version does not make beta versions available.
- The Laminar version of X-Plane does not mix and match with your version ie you can't use your version and try and download a beta version from Laminar. Just does not work.
- If anyone tries to purchase your version from Laminar Research they are directed away from their site as they do not sell it.
If you do have a "full" steam version then you need to make direct contact with the reseller or steam to get your product key. Have fun.