This is a setting call "Autosplit pages" in Global Settings
1. Click on Settings => Global Settings from the Menu on the Toolbar.
2. Under Settings for this website, click on Miscellaneous to see the window above
3. Enter the number of products or Paragraphs you want to display on one page in the box (as pictured above).
4. Click the Ok button to save your changes.
5. If you want this setting to apply to all websites you build with ShopFactory then you can also change it in New Settings => Miscellaneous (in the window above)