I would recommend you to stay with Mercurial or something else, but it always should be Open Source. The reason is not just money for the license. You cannot trust such critical assert as you code base to something which is proprietary and without source code. The biggest team using Open Source Revision Control systems tent to be much bigger. Thanks to open nature of the product, millions interested developer do their best to lick such code clean.
I would advise to consider Subversion, Git, Bazaar and Mercurial first.
Among other things, they are also very light-weight and flexible. Subversion needs a server, but code base can easily be moved across servers and different platforms without any risks. I also use it on every local computer, as a server. Many other systems can use Subversion storage system. Other three systems can be used in both centralized and distributed. The concept of distributed Revision Control System is very interesting and robust.
Please see this discussion first:
Revision control systems, which to choose from?[
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See also my recent answers:
Needs some words of wisedom to set up and/or use a server[
^],
Make an unclickable form[
^],
How can i structured to arrange source code when i create a new solution[
^].
Don't wait. Set aside all what you are doing and setup version control until it's too late.
—SA
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