Isso é do artigo da WinZip KB .
Customers who purchase a multi-user license will receive a unique
WinZip.wzmul registration file which must be copied to a WinZip
subfolder in the Windows Common AppData folder. This folder contains
application data for all users. For Windows 7 and Windows Vista, a
typical path for the WinZip.wzmul file is C:\ProgramData\WinZip. For
Windows XP and Windows 2000, a typical path is C:\Documents and
Settings\All Users\Application Data\WinZip. The presence of
WinZip.wzmul in this folder will convert WinZip to a licensed,
registered version.
Portanto, coloque seu arquivo WinZip.wzmul dentro de C: \ ProgramData \ WinZip e o aplicativo deve abrir e reconhecer seu status de registro muito bem.