storefront-echo-1.4.1

Hi I am running storefront echo 1.4.1 with wpec for products.
I would like to use your plugin after trying it on a dev. site.
Heres the thing if you could help,
My products are QR Codes, each unique with there own serial numbers.
The Personal QR Codes are free, I would like to be able to download a QR Code in maybe a PNG. format and a serial number for activation how would I use your plugin for this?
Thanks in anticipation.

http://wordpress.org/extend/plugins/easy-digital-downloads/