I don't know why you think this will help prevent piracy, Im sure it won't, and it just creates pain for the people who purchased your assets. Its a very bad idea and Im very sorry you decided to do this. I mean the pirates are mostly getting the assets from someone who has purchased them, so eventually the pirates will get hold of the documentation and share it. The asset pirates are extremely annoying but history mostly shows that trying to fight piracy in this way causes little good and plenty of inconvenience for legitimate users. As someone who has spent lots of money in the asset store, including UniStorm, I do get upset by the pirates. But I don't want even more reasons to be upset, or to think of people spending lots of effort trying to thwart the pirates in ways that are doomed to fail. Never mind, I keep my invoices so I will be able to get the documentation, but I still think you should abandon this idea, focus on making life nice for your legitimate users and never mind the people who won't pay.