I registered a copy of Soldat v1.2.0 and then I patched it to v1.2.1 and it left the settings that I changed but it wouldn't let me use them and it says that it's no longer registered. Does anybody have any ideas on what I can do.

Run the registration key again or message Michal Marcinkowski about it.

Don't bother to do any of those things if you've given away your key to others or if you haven't actually bought it.