Product & variant limits
There is no overall limit to the number of products you can list on your store.
However, there are a couple of points which you may like to know which are related to this.
These are Shopify platform-wide limitations and are not theme-specific whether premium or free.
1) Shopify has a limit of 50 items per collection page, but adding pagination overcomes this.
More information on this can be found here: Shopify Help - Pagination in Collections Guide
2) Variants are limited to 100 per product (mentioned at the top of this guide): Shopify Help - Variant Limits Guide