About SourceSafe licenses
What you really need is a real source control system .
I don't stand on ceremony or neglect here. SourceSafe is better than nothing, but almost every other SCCS is better than SourceSafe - there were reasons why MS did not use it internally (for example, high risk of database corruption, inefficient use of files, lack of support for branching). TFS is pretty decent (maintained by MS) and many swear by Subversion. There are many other tools as well, many of which integrate with VS.
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Remember that VSS is often criticized for its shortcomings. You might want to consider another VCS, for example. SVN or git.
See How do I convince my team to ditch sourcesafe and switch to SVN?
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Are you licensed through MSDN? If so, the subscription is "Visual Studio Professional with MSDN Premium" or "Visual Studio Professional with MSDN Professional" .
However, I also repeat the suggestions to see other suggestions. I prefer VisualSVN Server + TortoiseSVN (client)
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