What happens if someone exceeds the days per move in Daily Chess

Let's say I've set it for 3 days per move and for whatever reason my opponent doesn't make the move in the allotted time?  Do they forfeit the game?  Is their turn skipped?

Yes, I can set the time limit for longer, but that doesn't answer the question.  What happens if the time limit per move is exceeded?

Vacation will kick in, and then they lose on time.

For a tournament game, that allows vacation that holds true if the members is premium. For non-tourney games, it will go to vacation for premiums and if the setting Automatically claim victory when time runs out! in the Daily Chess settings on the website is off, nothing will happen unless you claim the game or 60 day has passed with no moves.

If a player does not move in the time control they lose on time - in your daily settings is an option to 'automatically claim win on time'. If this is on you get the win when their time expires. If it is off then you have to go into the game page to claim the win, so if you are offline when your opponent times out then they could still move after their time has expired. The exception is in games/tournaments where vacation time is allowed. All paying members get a certain amount of vacation time and when they are down to very little time in daily games they will automatically be put on vacation. The game is them effectively paused until they return or they run out of vacation time.