How long an access token lasts

Generate Access Token now explains token lifetime:

• A token has no fixed expiry, and the response doesn't include one.
• Requesting a token again returns the same token while it's valid, so request it at the start of each sync run instead of storing it indefinitely.
• Rotating the API secret or deactivating the account revokes it. When a call returns 401, generate a new token and retry once.

The access_token field and the Authenticate and make your first call recipe say the same.