Hi. We get freeplay from MGM properties (NYNY, Treasure Island, Mirage, etc.) and once you go to the Players Card booth, they put the credit in your personal card. Once you insert in a machine (progressives are not eligible) the credit shows up. You will have to put a $10 bill to get started. You can pull out the ticket anytime and move to another machine.
At the Venetian, you go to the players booth for the credit. BUT, you can only play the $$$ on one machine. If you pull your card and move to another machine, you will lose the remaining freeplay credit. You can keep cashing out each time you hit something good - just don't remove your card.
On one of our trips we had $100 freeplay and played a $1.00 machine with a "triple" pay symbol and ended with $515. I'd like to know which casino is giving you freeplay. Both of the two above mentioned properties also give you cashback at the end of your stay. Almost like getting freeplay again. Harrahs mails you a cashback check that you have to return to redeem. The cashback voucher is usually not as much as we get at the other properties. So, they must use a lower percentage. Not too good. GOOD LUCK.