downloadable products already purchased

suggestion

if download is available for the purchased product, a download button should replace the add to cart and sample download.
and if the purchased download is not available a message should displayed in the product page and product box

many customer does not know about the downloadable product link in the my account menu.

in any case I have updated Download Button plugin for the 3.8 version
u can download for free at:
http://www.hezyziv.com/download-button

the plugin add a download button to the product page in cases product was already purchased and download is available