Executing a file in memory only

Is this possible with NSIS? Lets say I wanted a file for a user only to demonstrate, only open one time, and to do this, it could not be written to his harddrive. Is it possible to execute files directly into memory with NSIS?

no, nsis can not do this. (It is possible in theory, metasploit does it, but you have to be a pretty good coder to implement it, and it uses undocumented functions)