We currently have two active codebases. ProEssentials v8 and v7.
Pick your version of interest:
1) ProEssentials v8 : Released on June 24th, 2014. We are working on free additions to v8.
2) ProEssentials v7 : Released on Feb 20th, 2010. No longer getting new features, and resolving anything needing attention.
3) ProEssentials v6 : Released on Jan 10th, 2007. No longer getting new features, we will fix anything major in that rare case.
4) ProEssentials v5 : Released March 30th, 2003. We recently updated to resolve Win7 breaking v5 but no more changes are expected.