Upgrading from Free Trial to Permanent Access

Hello,
I've been using the trial version of Parallels for school on a daily basis. When my trial expired today I purchased the full Student version. When prompted for my key, I received a notification saying what I used was an "upgrade key", and my initial service code was required.
I no longer have access to the key I used for the trial version. How do I follow through with upgrading the the full student version with out it?

 

It seems you have purchased an upgrade key not a student key. Student key is only sold on www.onthehub.com website. If you purchase an upgrade key, you will need use Parallels Desktop 11/12 as a previous key to complete. If you don't have a valid previous key then get refund and purchase a full version

 

Ohhh it is very pitty situation as for me(

 

You can share the issue you are facing with us to check and assist you further.