First, I should explain what PRTG is for readers who might not be familiar. Then, discuss the licensing models. PRTG has different versions: the free edition, the commercial edition, and maybe others. The key point here is the free exclusive license key. Wait, is there such a thing? Or is the free version considered the same as an exclusive license? Maybe the user is referring to the free edition, which allows unlimited sensors but has some limitations compared to the commercial edition. Let me check that.