I received confirmation from their support that if you decide to close your account, and you have any money in your account below the minimum payout treshold ($60), they'll KEEP the money.
So make sure you've reached this minimum payout treshold, get paid and only THEN close your account.
The other bad news is that it takes ages to reach minimum payout due to lack of sales, so your money may be kept hostage forever (until they shut down...)