In a sign that the cloud has hardly erased the importance of cross-platform interoperability, security and identity management vendor Centrify has announced some key changes to its product for connecting Linux, Mac OS X and other Unix servers and desktops to Microsoft Windows Active Directory (AD).

The updates include two major changes for users of Centrify Express, a free-to-use tool that makes it easy to join Unix systems to AD domains. First, organizations may now deploy Centrify Express on a maximum of up to 200 Unix and Linux systems, or 400 for educational and non-profit institutions. (There is no limit on the number of Mac systems that may be present.) The previous version of the end user license agreement (EULA) for the product placed no cap on the size of deployments.

In addition, Centrify removed some features related to access control from the Express product, and will now make them available only as part of Centrify Server.

Centrify Express will remain free to use, but the company has indicated it intends the changes to encourage more of the 130,000 organizations that it says are currently using the product to consider upgrading to the premium, paid version of the software. The move “will ensure that we can continue to offer a free solution, while offering a robust paid upgrade for those interested,” according to a company statement. “We believe these changes only impact a small percent of Centrify Express users.”

Centrify noted there is no mechanism in place that will actually restrict the number of sytems an organization may use with Centrify Express, so it likely won’t be enforcing this new part of its EULA on a large scale. Still, the company’s efforts to nudge organizations toward paid software licenses for Unix and Microsoft AD compatibility is a sign it thinks there’s still a fair amount of money to be made by making it easier to deploy Linux, OS X and Unix desktops in a Windows environment, even in an era when cloud computing has decreased the significance of barriers between operating system platforms.

At a time when Linus Torvalds is calling for more focus on desktop Linux, Centrify may be right.