Your product information is stored as Master data and there are no limits imposed on the number of products you can store in Master data.

Limits are only imposed to the number of "SKUs" or "Products" you are syncing with a specific retailer.

Eg:
​Retailer 1 - 100 SKU Limit
Retailer 2 - 500 SKU Limit

You should select the plan that best covers the total number of products you want to sync with that particular retailer.