This is one of the reasons I don't like software from this vendor [in 2 words: old tech]. Another is the amount of spam.
That said, you can see here the relative age of WMEncEng.dll
support[.]microsoft[.]com/en-us/kb/929182
And/or that page might also provide a way for you to easily install the file.
As far as registering a file with Windows, there are 32 bit & 64 bit versions of regsvr32.exe -- one is always in the C:\Windows\ System32 folder -- in 64 bit versions of Windows the 32 bit version is found in the SysWOW64 folder, with the 64 bit version in System32. You can register a file manually using the command line [running cmd as admin in Windows Vista +], navigating to the proper folder for the version of regsvr32.exe you need, then just typing for example regsvr32 [path]WMEncEng.dll, where path = the path to where that file is found.
Google & there are instructions & utilities & modifications to Windows context menu you can also use. If the app seemed to install otherwise in Safe Mode, back in full Windows you'd find that file & try registering it.
I don't know whether it would work -- I don't know if the version of WMEncEng.dll it tried to register is compatible with your version of Windows etc., but registering it manually would be what I would have tried next in XP or Vista.