You need to post WHICH version 13... Windows or Mac, and if Windows 32-or-64bit... so someone who might be interested will know what you are selling
And, if you installed and activated, you need to complete a program transfer per Can Creative Cloud members pass on or sell old versions of CS?
From whom did you purchase Premiere Elements 13? If from Adobe, you should be able to get your money back within 30 days of purchase.
Are you aware of the Adobe Licensing Agreement and the transfer of License to another? Please check out the following
Do you know that you can export a file with 5.1 channel sound from Premiere Elements? Not Dolby Digital 5.1 channel, but you have some opportunities
for a AAC 5.1 channel and some others as described in the following
In that same blog are a few other blog posts on the subject if interested.
But, if export with Dolby Digital 5.1 channel is your only focus, then try for your money back and next time first go the tryout route before
purchase to assure the compatibility of your program with your computer and project goals.