Well, you're asking a bunch of different questions and I'm not sure where you're stuck.
If I have "SetOutPath $PLUGINSDIR" before calling the dll, $2 returns "1"Perhaps this error means it cannot locate the dat file.
A return code of 1 means a general error (On TurboActivate.h in the "API\C" folder to see all the errors and what they mean). It's almost certainly that the product key you're passing in is invalid.
The temp folder created by setup.exe contains all both "TurboActivate" files and other dlls. I would like to distribute just the setup.exe file to users. Is there a way around this?
The design of NSIS is to include any dlls that will be called, then, when the installer is first run, extract these dlls to a temporary folder so they can be accessed. This is the design of NSIS, there's no way around that.
The temp files are deleted when your installer closes.