The Product Lifecycle
The same decision can be smart one year and foolish the next. Spending heavily on advertising before ReShelf works would burn money; refusing to spend once students flood in would hand the market to a rival. The product lifecycle tells you which kind of year you are in.
The rule
Each stage asks one question: build, prove, grow, defend, or renew.
| Stage | Usage | The PM's main question |
|---|---|---|
| Development | None yet; money only goes out | Does it solve a real problem well enough to launch? |
| Introduction | Low and slow; people must discover it | Do early users keep coming back? |
| Growth | Rising fast; rivals notice | Can we scale before quality breaks? |
| Maturity | Flattening; competition is fierce | How do we defend our place and run efficiently? |
| Decline | Falling; the need is moving away | Do we reinvent, harvest, or retire it? |
- Development: ideas become prototypes and a first version. There is no revenue, only cost.
- Introduction: the product launches. Few people know it exists, so the job is proving that those who try it stay.
- Growth: word spreads and usage climbs quickly. The risks shift to the product breaking under load and competitors copying you.
- Maturity: most people who will ever use it already do. Progress comes from winning share, keeping users loyal and running more cheaply.
- Decline: a new technology or habit pulls users away. You can reinvent the product for the new world, harvest it (keep it running with little new investment), or retire it gracefully.
Not every product visits every stage, and a stage can last months or decades. The point is to match your priorities to the stage you are really in.
The shortcut
Read two signals: is usage growing, and how fast? None yet means development. A slow rise means introduction. A steep rise means growth. Flat means maturity. Falling means decline.
Year 0: no users
The team builds a prototype and tests it with 20 students. Development: fix the core flow.
The trap is misreading the stage: treating a flat, mature product as a failure and gambling on a risky rebuild, or pouring money into promotion during development before the product even works.
Drills
Answer fast — trust the rule.
ReShelf has launched on one campus. Sign-ups are slow, and the team is checking whether early users return next semester. Which stage is this?
Usage has been flat for two years and a rival has copied ReShelf's best feature. What should the PM focus on?
Which stage has costs but no revenue at all?
Printed textbooks are fading and ReShelf's sales fall every term. Which is NOT one of the usual decline options?
Sign-ups are doubling every semester and the app crashes during orientation week. What comes first?
Remember
- Development, introduction, growth, maturity, decline: build, prove, grow, defend, renew.
- Shortcut: read whether usage is growing and how fast, then name the stage.
- Trap: using one stage's priorities in another, like heavy promotion before the product works.