I guess you are referring to the scam websites. There were bunch of similar websites as you are talking about.
Website that gives like free code of several dollars free for registration.
Then users are asked to play on their roulette game to complete the wagering requirement.
After users complete the wagering requirement then users will be asked to deposit some amount of money in order to withdraw the money won from the free code.
If it is correct, simply forget it. No reasons for you to remember it.