If client based application need to be developed then below are the DLL files needs to be used at client side

dll must be in system32 are for window based .net application

NBioBSP.dll
NBioBSPCOM.dll
NBSP2Eng.dll
NImgConv.dll
BioEnable.dll

and if customer is making any web based application where communication is done using web interface then below additional file need to be used

BioBSPCOMM.dll. This file should be in GAC