When you download and install a new version of EasyWorship (for example you have EasyWorship 2009 or EasyWorship 6 and you install EasyWorship 7), it will install separately from the previous version.  It will not overwrite what you already have installed on the computer.  You also will not lose any of your database (songs and media).  As long as you are installing on the same computer the database will convert into the new version.