For this reason alone, Betfair has no reason to ban or close your account when you should win. This is what Betfair first became famous for; peer-to-peer betting. Whilst the Exchange account won't be closed for winning, there is an additional commission rate.
One of the most important tips you could consider when playing roulette as a casino newbie is sticking to the table minimum and focusing on only playing the outside bets. Bet on either black or red for every new spin and you will enjoy a 1:1 payout while covering 18/38 potential combos.