Here's the timeline behind a missed payment, and what's actually at stake if it isn't sorted out.
The grace period
A failed charge starts a grace period - 5 days by default, the same length regardless of which plan you're on. Sending is suspended as soon as the grace period starts, not deferred until the end of it. There's no automatic retry and no cap on how many times a charge can fail - it's on you to update your card or pay the invoice within that window.
If it's not resolved in time
If the grace period runs out without payment, your subscription is cancelled automatically.
Already in this situation? Here's exactly how to fix it. Why was my payment declined? →
Wondering why your sending stopped specifically? Why didn't my campaign send? →