Visual Assist is not officially supported in environments with multi-user access, e.g. provided by Citrix, but you may have some success with the instructions in this article.
Note: You must have one license of Visual Assist for each developer connected on a multi-user PC. It is a violation of the software license agreement for Visual Assist to install a one-user license on a PC that serves multiple developers.
Visual Studio 2010 and newer
For security reasons, Visual Assist installs as an extension to the IDE for the current user only. This limitation of all IDE extensions prevents one from installing a nefarious extension that steals or corrupts data of another user. Hence, if you install Visual Assist to an IDE in one user account, then publish the IDE to other users, the extension will not be visible to the other users.
The workaround is to install Visual Assist to an IDE, then copy the appropriate extension directory to a location the IDE reserves for trusted extensions. These trusted extensions are loaded for all users of an IDE, including those who launch the IDE via Citrix.
After installing Visual Assist to your IDE and entering an appropriate multi-user activation key, consult the Visual Assist documentation for the installation directory you need to copy. Once identified, copy the directory with admin privileges to the location the IDE reserves for trusted extensions. For Visual Studio 2013, this might be:
C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\Extensions
If you run Citrix, publish to Citrix and confirm VAssistX appears in the IDE menubar for connected users.
Visual Studio 2008 and older; requires administrator privileges
Visual Assist always installs to all users of the IDE, including users connected via Citrix. Hence, follow normal installation instructions for the executable (.exe) version of Visual Assist and install the extension to pre-2010 versions of Microsoft Visual Studio.