HotPixel
You didn't bought the "Personal Edition", you bought the "Personal License" <img src="smileys/smiley2.gif" border="0" align="middle" /> Just kidding
1. Go to "My Purchases" and download the license
2. Put the license where Construct 2 is installed on your PC
3. ...
4. Profit <img src="smileys/smiley36.gif" border="0" align="middle" />