Your monthly price is based on the number of products, what exactly counts as a product?

Our app counts all products in your Shopify inventory (from all sales channels, visible, invisible, in stock and out of stock). Basically, we store and sync all products in our database to make sure that we don't miss anything when you update a product, set it visible or publish the product to the online store channel.
We do not count variant or SKU. If a product comes in three size variants (small, medium, large), we count it as 1 product.