ElaineMarley86 on "[Plugin: eShop] Buy item just once"

I'd like to disable the possibility to buy an item twice for a user: when that item is purchased the user can't purchase it a second time. Is it possible to do something like this?
I know I can set the maximum quantity but that doesn't work for me, because a user can simply buy a single item, pay it and then go again on that item page and buy it a second time.
Thanks!

http://wordpress.org/extend/plugins/eshop/