I can't activate my Impreza license


I got back an Impreza licence from a website that I had to delete. I wanted to activate it on an other website (after deactivating it from the first one, of course). Whenever I click on “activate Impreza” to enter my license number, it redirect me into the Envato support portal and ask me to log in but I cannot (as my support is no longer available because I only had few month trials). How am I supposed to activate my licence then ? Where do I have to put my number ?

Thank you,