QBSE doesn't have any feature to track the inventory. You may have 2 options:
1. Migrate to QB Online Plus or Advanced.
https:// quickbooks.grsm.io/US
https:// quickbooks.grsm.io/us-promo
2. Utilize an inventory management app. But you have to migrate data (i.e expense transactions) manually to QBSE.
https://go.tradegecko.com/register?code=fiat-lux