With credits, you can play for as many spins as you wish; you may also bet multiple times on a single spin button. The maximum that you can bet on any single spin button is twenty dollars. Once you have bet the maximum, the spin button will stop functioning and will not give you another chance to bet more.
You may enter your starting deposit at the start of each game and this will keep increasing as you proceed to spin the slot machines. There is a maximum daily jackpot amount in online casinos and these amounts keep changing. Once you hit the jackpot you will be automatically removed from the line and your position will be transferred to the next player in line. The only way to get yourself off the line is by winning a jackpot.
There are some limits when it comes to playing free slots with credit card payments.