Each Rewards campaign will have a finite number of users, depending on the number of claims you have configured, or the number of coupon codes you upload.

If you upload 100 unique coupon codes, then a maximum of 100 users can each claim a unique code.

If you configure for a single code to be claimed 100 times, then a maximum of 100 users can access that same code.

Number of claims are restricted to one claim per unique IP address.