Like all software vendors selling Enterprise software packages, the introduction a new version can bring changes to packaging, licensing and most importantly pricing. Lync 2013, the latest version of Microsoft's communication services product is no different.
Directions on Microsoft have produces a nice paper on these topics. However, like many research houses, the report is behind a pay-wall at http://www.directionsonmicrosoft.com/licensing/30-licensing/4553-lync-server-2013-packaging-licensing-and-pricing.html/
The good news is that you can get a guest member logon for this site which gives you 2 months use of the site for free. Full membership is US$1645 per year. This is way out of my league although the information would indeed be useful. I’ve signed up for a guest membership and we’ll see how that goes.