The game is free, always. A pass is for the night you want the television to look like yours — your artwork, your title, your tip code.
One pass is twelve hours of running time, and as many games as you like inside it. It starts when you press Start, not when you buy — so buying on Tuesday for a Saturday party is the ordinary way to do it.
Passes do not expire. Buy five, play one tonight and the last one next spring. They live against your email address, so they follow you to another laptop rather than living in one browser.
The whole game is free without any of this — every card, every draw, the saved games, the bundled decks and themes. A pass changes how the night looks, never how it plays.