https://developers.smartsuite.com/docs/solution-data/webhooks/webhooks-overview#webhook-expiration
Webhook Expiration
You must call list payloads at least once every 7 days for the webhook to stay active. After 7 days of inactivity we will disable notifications for your webhook. Webhooks in this state for a further 7 days will be deleted, along with their payloads. Calling list payloads during the 7 day inactive period will re-enable the webhook and extend the timeout period an additional 7 days.