How do you link a new account to a previous Hitfilm purchase?

So I recently made a new Hitfilm account. I did so, because I recently changed my email, and my previous account used my old email, but I couldn't remember my password for that account, and I couldn't send it to myself since my email was changed. So I've made a new account, and I'd like to know how I can link the new account to my previous purchase of Hitfilm 2 Ultimate. I'd like to link it, so I can upgrade my purchase.

Thank you.