Evandro Luiz, I had the same problem because I copied and pasted the registration key. I noticed the key is 5 sets of 4 characters each but it did not paste properly. Try copying the key again BUT use the little paste icon to the right of the key field. That fixed it for me. If that doesn’t work then enter each character by hand.
One tip for entering keys. When you copy/paste a key look carefully and your pasted key. Make sure you didn’t copy a trailing space.