OTO allowing members to see more than once

On a membership site offering one time coupons to members. Members log in with user name and password. Still in testing. If member reboots his phone he can see the coupon again. If he logs in from another device, he can get the coupon again. That probably has to do with IP Address. The coupons are redeemed for free goods and services so the merchant must see the failed notice once the coupon is used.
I have submitted support requests but have not heard from anyone.

If you look at site I will send you log in details.
Thanks,
Chet

The page I need help with: [log in to see the link]