Ok, you're Platinum so should be able to do this...
In the GUI or software, open the settings menu (The little cogwheel) at the top right of the gui. Make sure Advanced settings is enabled at the top left then scroll down till you see 'Clips'. Below right of this, you can set Free preview push to never.
Enjoy your girls. Stick around here long enough and you will learn just about everything there is to know about iStripper... 😍