Kinguin.net resells keys of.... dubious legitimacy. Often they are purchased with stolen credit cards and then basically fenced (and cancelled once the victim charges back), or sold in violation of their original licenses (for instance, VLM corporate keys). Kinguin is not a great place to get these, as you can buy them and either they don't work, or they will be cancelled months later when their checks or a sweep picks them up as being fraudulent in some way. Kinguin can maintain low prices due to the minimal liability they maintain for getting you working software, one of the reasons it is so exceptionally cheap versus other options, but it comes as a risk for the consumer. They don't care, they make their commission, and hopefully you won't do business with them in the future, because they help support a small industry of theft that hurts not only consumers like yourself, but innocent people, and the fees from chargebacks are eaten by the developers in some cases, hurting them too.
With that out of the way, let's see if we can try to help you, because while it's a mistake to order from Kinguin, you shouldn't have to pay the price for it. What version did you buy? What was the exact listing info from Kinguin? What version did you install? Please go to "This PC" and right click it, select "Properties" and let us know what edition it says there.
Once we have made a determination as to whether the key should be working outside of human error, we can move on to trying to activate it. If that process fails, well, you got an illegitimate key, at which point it is in your interest to contact Kinguin and if they don't get you prompt resolution, charge back on your credit card and do no further business with them.