How to limit the number of download purchases

[Guest]

I have a customer that is offering a FREE download product and we are noticing that people are over and over processing a new order to download the same FREE download.

 

Is there a way to determine if this person has previously ordered the FREE download to inform them they have already purchased the product or to limit their ordering of the same product over and over.

 

They really only need one FREE download since it is the same product each time they place an order.

 

I know frustrated once again, but I am sure there is a solution.