Upgrade / expansion prompts subject lines

10 examples

1. 1.You hit your monthly run limit early
2. 2.You just shared your 5th template
3. 3.About the feature you tried to use
4. 4.Your team is on Starter — should they be?
5. 5.Free tier is fine. Pro adds these three things.
6. 6.{{teammateName}} hit the credit limit
7. 7.Three users at {{workspace}} — Pro pays for itself
8. 8.About the API access you asked about
9. 9.You exported 12 PDFs this week
10. 10.Time to upgrade? Here's the honest math.

What makes these work

Upgrade-prompt subjects work best when they're tied to a specific behavior that suggests the user has outgrown their current plan. 'You hit your monthly run limit early' is honest and specific; 'Upgrade to unlock more features' is generic and converts poorly. Subjects that reference a recent action ('You just shared your 5th template — that's a Team plan feature') feel less like a generic upsell and more like a genuine notification. Avoid bait-and-switch subjects (promising one thing in the subject, pitching upgrade in the body); they damage trust and lift unsubscribes.

Templates that use these patterns