Here is instruction to activate your Ddownload.com Premium Key!
1. You will receive a Premium key / Premium code like this: 1220s5e5cbo381XXXXX
2. Login to your Ddownload.com account (You should register your own account, if you dont have it, https://ddownload.com/)
3. Go to Profile page. (http://ddownload.com/?op=my_account).
4. Find Apply Premium Key field
5. Put your key here, then apply it.