To make sense of "free spins keep what you win", start with how the offer is built. A welcome offer is rarely one bonus. It is usually a package spread across several deposits, each with its own match percentage, ceiling and conditions, and sometimes with free spins attached. The headline adds the parts together, which makes the whole look larger than any single step. Taking the package apart shows what each deposit actually earns and what it asks in return.
Every offer names a qualifying deposit, a minimum below which no bonus is paid. Some also require a code at the cashier or a tick in an opt in box before the payment, and a deposit made without it rarely earns the bonus afterwards. Certain payment methods, often electronic wallets and prepaid cards, are excluded from welcome offers in the terms. Checking the method and the code before paying avoids a deposit that quietly earns nothing.
A match bonus adds a percentage of the deposit, up to a ceiling. A hundred percent match up to a stated maximum doubles a deposit that stays under the ceiling, and adds nothing to the part above it. Higher percentages usually come with lower ceilings or heavier wagering. Comparing offers by the bonus a planned deposit would actually receive, instead of the largest figure in the banner, keeps the comparison honest and often reverses the order of two competing offers.
Asked about this
Why do no deposit bonuses have tight conditions?
No deposit offers give credit or spins for simply registering, so casinos pair them with high wagering, a low withdrawal cap, a short deadline and one claim per household.
Why does the opt in step matter before depositing?
Some offers only apply when a box is ticked before payment, and a deposit made without opting in usually earns nothing afterwards.
Is there a minimum deposit for a welcome bonus?
Every offer names a qualifying deposit, and a payment below that minimum earns no bonus at all.
When does a bonus code need to be entered?
Some offers need a code at the cashier or at sign up before paying, and a deposit made without it rarely earns the bonus afterwards.