Hypothetical question about revoking SB

So, let's say there's an offer that asks you to sign up for an account, to deposit $5 and you have to keep the $5 in the account for 30 days of else your SB gets revoked but what happens if you got the SB within a day and already redeemed it for something and then you decided to withdraw the $5. What happens then, there's no SB to revoke, do they take money from your PayPal or something?