Friend, Please forgive my response being 11 months late, but this is the first time I saw your question. Maybe I can help you. If you purchased and downloaded Acid Pro 10 online, what I'm about to tell you may be a solution to your question. After your purchased of Acid Pro 10 online, Magix sent you an email receipt for your purchase. That email was called "Confirmation of your order from Magix" and that email was your receipt. If you look carefully, at that receipt you will see that you were provided with not only the serial number for the main application being Acid Pro 10, you may or may not find a complimentary Coupon code for an additional loop Collection, ( a promotion inducement that Magix was using at the time of my purchase) and below that bonus coupon code, you will find the Celemony Melodyne 5 Essentials serial number.or activation code. These two numbers are one and the same. I hope that this information is of some benefit to you. When I first downloaded Acid Pro 10, I jumped right in, as soon as I got it "sort of up and running", I started to play with it. I figured all was good and the rest of the instructions were tossed to the side. That kind of behavior behavior was so easy for me to fall into. I myself had to go back and dig thru all the Acid / Magix emails and pages I printed off to find exactly what you and I were both looking for. Have a great day.