If you purchase a license now, you will get version 5 as well: There's only one version of REAPER. One complete, solid, full-featured digital audio workstation. Your one-user, full-use license includes up to two major version numbers' worth of REAPER's famous frequent upgrades. Purchasing a license now includes upgrades through REAPER 5.99. REAPER 3.0 licenses purchased in 2009 are still valid for REAPER 4.x, and have seen over 100 free upgrades and counting.