(This is a Chinese bbs forum. If you have staff who know a lot about Chinese, you can make them read it. If not, it's ok, and I'll explaint it in the COMMENTS area).
This is an article in one Chinese college forum, and the author just posted a messgae about yoursite.
As you may know, Digital Ocean is just making a education pack with github and is providing a 100$ promo code for students. And the author, is going to make a long list of how to make use of it, however, she is just giving a way of using one's own edu e-mail, borrowing one edu email from others, and even cheating to use a fake edu email(which can be bought from TAOBAO-ALIBABA, the Chinese version of EBAY). At the end of article, she also gave a way to use the host to get access to the Internet through the Great Fire Wall in China, using a SSH method, which in my opinion is an abuse of our host and may do harm to others using your service.
Besides using unhonest(cheating) methods to earn the credit card, she also gave her own referral link to advise others to register using the link. Maybe the real reason she gave the posts is to earn the credits.
I know about her, and it takes me a few days hesitating whether I should report this to you. Finally, I give you this feedback, but I use an Anonymous letter, please forgive about this. The post is listed on Oct.16, I hope you can do something before it is too late.
As my suggestion, I suggest to give a wise judgement on the accounts registered using the referral link. Some of them may be students, but I'm certain that some are fake ones. Besides, the owner of referral link... you can decide by yourself.