How to Make Your Product A Habit
This whole theme is drawn from Charles Duhigg's book The Power of Habit.
What are habits?
“The choices that all of us deliberately make at some point, and then stop thinking about but continue doing, often every day.”
The Habit Loop
The habit loop is a well-documented loop that underlies our habits:

Cue: Something that triggers a behavior (like seeing a candy bar in the checkout line at a store).
Routine: The behavior (purchase and engulf said candy bar).
Reward (sugar rush, deliciousness, etc.).

But a key part of the loop is a craving or anticipation of the reward. Say in the above example you see the candy bar and start to reach for it, but some little kid grabs it and runs off- and it's the last one! We saw the cue, but now we can't enact the routine... and we're left craving that chocolate goodness. So for a habit (loop) to be effective, the cue needs to be strong enough to trigger that anticipation.
Marketing based on the habit loop
Below are just a few examples from Duhigg's book.
Pepsodent
Claude Hopkins was brought in to sell pepsodent. Hopkins was one of the greatest advertising executives known. He was well-known, too, for his two rules for marketing:

Find a simple and obvious cue.
Clearly define the rewards.

Sound familiar? That's because those are the first and third parts of the habit loop (cue and reward). Hopkins' challenge was that Americans didn’t brush their teeth back in the early 1900's (I love Catherine's reaction in the show). But he figured out a way. Hopkins's ads in the 1930's exploited "tooth film" - a naturally occurring coating on teeth that everyone gets - as a trigger. Brushing was the routine, and a more beautiful smile was the reward. “Just run your tongue across your teeth,” read one ad. “You’ll feel a film—that’s what makes your teeth look ‘off color’ and invites decay.” Pepsodent spiced up the reward with citric acid, mint oils and other chemicals to enhance the cool, tingling taste, To reiterate how this fits the habit loop:

Cue: Feel your tooth film.
Routine: Brush with Pepsodent.
Reward: Be more beautiful.

But the real kicker was the craving Pepsodent created. By adding mint oils and other slightly agitating chemicals to the toothpaste, consumers felt their gums and mouth tingle after a brush. That's what people craved- the cool tingly sensation in their mouth. Once other toothpaste companies got wind of people's craving for that tingle, the other companies started adding those elements to their toothpastes.. and started selling a lot more.
Cinnabon
Cinnabon purposefully distances itself from food courts in malls. That' so the sweet smell will attach consumers' nostrils in isolation, a clear signal that sugary goodness is around the corner The habit loop:

Cue: The smell of Cinnabon.
Routine: Buy and eat a cinnamon bun.
Reward: Sugar rush.
Craving: The smell reaches far down the hallway, so you are smelling it for a while and anticipation builds.

We give one more example in the show- Febreeze. You'll have to listen to hear it!