As with any Windows .dll, you can check its version by simply right-click on the file, select "Properties", then "Details".
However, if you just launch any of our installers, provided is fairly recent, they all have an automatic online udpate feature, so its always gets the latest version of the .DLL so, you don't need to worry not having the latest version, because the installer will always get it for you. Of course, you need to run the installer with an internet connection active.