Look like copy.com has silently changed their referral policy and now You can’t get more than 40 GB (earn 5 GB, for a maximum of 25 GB) of free space by referring friends.
UPDATE: service is discontinued :(
I was lucky to get more than that for my freelancers account, but since moved to “internet only” file storage for personal files, cloud space became essential.
This also requires to change strategy on referral new users to copy.com;
Anyway, here is link to my referral https://copy.com?r=1SKtNm You can still get Your extra 5 GB;