make sure you are using the same E-mail and Password when you got WB 6....
Try going here https://www.stardock.com/
Under Popular Software look for WindowBlinds click it then click on BUY NOW
sign in with your E-Mail and Password
look for UPGRADE at the top right
then a new page will load put in your
E-Mail Address
and
Product Serial:
hope this helps
On another note, I want to know, if windows blind is incompadible with nvidea driver 257.21
it will work just fine.. but I have not did the driver update yet.. the only app that I can think of that will / may use your Graphices card is DeskScapes