Where to put serial number? (trial expired)

So, a little while ago, I downloaded the Photoshop cs6 free trial. I played around with it, and eventually, yes, it expired. It was only a few hours ago did I decide to actually buy the product. Now that the trial has expired, I am not entirely sure how to enter the needed serial number, as on Creative Cloud, all it says is "Trial Expired".

What exactly to do...?