> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upstackdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# subscription_initial_purchase Event

> Track when a customer's first subscription payment is processed.

Fires when a customer's first subscription payment is processed (distinct from trial conversion). Use this event for acquisition revenue metrics.

## JavaScript

```javascript theme={null}
window._upstack('track', 'subscription_initial_purchase', {
  subscriptionId: 'sub_def456',
  accountId: 'acct_abc123',
  planId: 'plan_pro_monthly',
  planName: 'Pro Plan',
  value: 9900,
  currency: 'USD',
  billingInterval: 'month'
});
```

## Properties

| Property        | Type   | Required | Description             |
| --------------- | ------ | -------- | ----------------------- |
| subscriptionId  | string | Yes      | Subscription identifier |
| accountId       | string | Yes      | Account identifier      |
| planId          | string | No       | Plan identifier         |
| planName        | string | No       | Plan display name       |
| value           | number | No       | Payment amount in cents |
| currency        | string | No       | ISO 4217 currency code  |
| billingInterval | string | No       | `month` or `year`       |

## When to Fire

* First subscription charge succeeds
* After trial converts (first paid billing period)
* When new customer's initial payment processes

<Tip>
  Use `subscription_initial_purchase` for acquisition metrics and `subscription_recurring_purchase` for retention/LTV analysis. Together they give a complete picture of subscription revenue.
</Tip>