allows apply barrier buying code codes download expiration free generate high huge implications kids limit limits link money multiplied particular price product purchased quantity security severe stock tickets transaction twice unit

I have FREE kids tickets i.e. the price is $0. I know last time when someone tried buying two kids tickets he couldn't do in one transaction because your code allows for only 1 unit of anything that is $0. He has to do that transaction twice.

There are severe security implications in doing this.

Since the product is free, someone can enter a huge quantity (there's no money barrier) and make your product go out of stock, take away all the tickets/codes, generate a download link with high expiration limits (as expiration limit for a download gets multiplied by quantity
purchased).

Not all of that might apply to your particular product, but I guess you get the idea.