Several Best Service products work only with their inhouse BEST SERVICE ENGINE. This is included in such products you buy from SudeepAudio.com. 

• for Windows 8 or higher (VST 32bit & 64bit, AAX Native 64bit in ProTools 11+), click here
• for Mac OS 10.14 or higher (AU & VST & AAX Native in Pro Tools 11+, all 64bit), click here

Latest Best Service product installers are available here