From uber,
Remember, personal invite codes should only be used for personal and non-commercial purposes. This means that you can share your invite link with your personal connections via social media where you are the primary content owner. Public distribution on sites where you are a contributor but not the primary content owner (e.g., Wikipedia, coupon websites) is not allowed. Promoting your referral code via Search Engine Marketing (e.g., AdWords/Yahoo/Bing) is also not allowed.
Uber reserves the right to suspend your account and revoke any referral credits if they were earned against our terms.