Looking up "free spins bonus" usually happens after a bonus has vanished, taking its winnings with it. The cause is almost always a condition in the terms: a deadline that passed, a withdrawal made too early, a cap on winnings or a clause about irregular play. Each of these can be seen in advance, and a few minutes with the terms show which of them apply to any particular offer.
Requesting a withdrawal while a bonus is active often cancels the bonus and everything won with it, and some casinos apply the rule even to cash deposited alongside it. A player can usually cancel a bonus on purpose from the account page, which frees the cash balance at the cost of the bonus. Knowing where that option sits, and what it removes, turns an accidental forfeit into a choice made with open eyes.
Every bonus has a deadline, and usually two: one for claiming it and one for completing its wagering requirement. When the second passes, the bonus and any winnings still tied to it are removed, however close the requirement was to completion. Deadlines range from a day for free spin winnings to several weeks for a large match. The clock often starts at the deposit, which means a slow first session already uses part of the available time.
A saved copy proves which version of the terms applied on the day the offer was taken, which matters if the casino later changes them.
Usually not. Opening more than one account per person or household is a common abuse clause, and it can void the bonus and its winnings.
The bonus and any winnings still tied to it are removed, however close the requirement was to completion, and the clock often starts at the deposit.
A saved copy of anything support agreed settles disputes far better than memory, especially if the promise is later questioned.
A limit on how much can be withdrawn from bonus winnings, often a multiple of the bonus or a fixed amount; anything above it is taken back at conversion.
Typical examples include betting both sides of an even money bet, switching to low risk play to clear wagering, or sharply raising stakes after conversion.