However, I want to clarify that I couldn't find any specific academic paper or article with this exact title. It's possible that the paper you're thinking of might be a blog post, a forum discussion, or a technical write-up.
The term "patched" in this context implies that Ubisoft released updates or patches to fix vulnerabilities that were being exploited by activation key generators.
When a game is released, its developers and publishers often work to patch vulnerabilities and prevent cracking. In the case of Assassin's Creed 2, Ubisoft likely implemented various measures to prevent activation key generators from working.
That being said, I can try to provide some context and insights related to the topic.