It's pretty nice of you that you've shown me the referral test page. However, the problem currently is, that I don't have an effective anti-cheat mechanism. And I can promise you that people will try to get these rewards by cheating. So we need a proper mechanism for automated rewards.
My suggestion would be that if the new player reaches a special total level (500?), the referrer will be rewarded with member days. Thoughts on that? Or we go the hard way and confirm all referrals manually to ensure nobody is cheating.
That's why I suggested that we start off with a reward that would only be useful if the person is not cheating. You can consider it an initial version that can't be abused and then we can think of ways to add other rewards without people abusing the system to get those. I figured that instead of trying to stop cheating, we make it more costly than using it correctly.
Because if the referrer receives 6 member days when the referred uses a member ticket then the memberships would be active on both accounts at the same time, which means that the person would technically be getting 36 days of membership, but after 6 days there would only be 24 days of membership left on one account, because in those 6 days the membership was running out on 2 accounts at the same time.
If the person creates 2 accounts both referred by the same account and uses a member ticket on each of the alt-accounts, then after 12 days there would be 2 accounts with 18 days of membership left (only the ones that used the member tickets) and after 30 days all accounts would've run out of membership.
If someone creates 3 alt-accounts and uses 3 member tickets, then after 18 days there would be 3 accounts with 12 member days left and after 30 days all would have run out of membership. The cheating just gets more and more costly as more and more member tickets need to be used and requires the person to play with more and more accounts at the same time.
Even if someone creates 10 alt-accounts and uses 10 member tickets, then after 30 days the person would've used 10 member tickets to only have 1 account with 30 days of membership left. Can someone play with a main account and 10 alt-accounts at the same time? I highly doubt it, so that person would be wasting a lot of money on member tickets, without being able to play as a member on all of those accounts.
Whereas let's imagine that someone invites a friend and that friend buys a member ticket, the person who invited someone would receive 6 free member days every 30 days that can be enjoyed, without having to worry about membership running out on multiple accounts.
Someone invites 2 friends, who remain members? 12 free member days every 30 days that can be enjoyed without having to worry.
Someone invites 5 friends, who remain members? 30 free member days every 30 days, free membership for as long as the 5 new people continue to play and remain members. If any of them quit, then the person has a reason to invite more people and even if none of them do then having 6 friends playing the game and getting 36 free member days as that person's friends use 6 member tickets every 30 days would allow to save up member days in case someone does quit.
My approach is pretty much this: Let them cheat but make it useless as they use more money to buy more member tickets and still run out of membership at the same time that they would've if they hadn't cheated.