from:

on *:load:{
  if ($version >= 5.90) {
    echo -a Successfully Loaded AdminScript [Version 0.1] By Country|Rocker
    echo -a To Use Right-Click Pop-ups.
  }
  if ($version < 5.8) { 
    echo -a Your mIRC Is Too Old, AdminScript Only Works With mIRC 5.9 Or Later.
    unload -rs $script
  } 
}

You could make:

on *:load:{
  if ($version >= 5.90) {
    echo -a Successfully Loaded AdminScript [Version 0.1] By Country|Rocker
    echo -a To Use Right-Click Pop-ups.
  }
  else {
    echo -a Your mIRC Is Too Old, AdminScript Only Works With mIRC 5.9 Or Later.
    unload -rs $script
  } 
}

Small tip, nice script though. :)