I bought kontak7 and downloaded it from native access. But no matter how much I look for it, I can't call it from Cubas because I can't find the dll file. It can be used independently, but it's not available at the moment at Daw. Please tell me how
Because it's an .exe file stored in your system drive under Program Files\Native Instruments\Kontakt 7
Note that Kontakt 7 (as a plug-in) is available as a .vst3, not .dll.
Is Kontakt listed in Cubase's VST Plug-In Manager? If not, have you checked the paths?