Both stores types have a paid plan to use Syncio. See details below for how the plans work for each store type, as the type of plan and metric differs.
Destination stores (stores that need to sync inventory) pay a fixed subscription fee, depending on the products synced from a Source store. Destination Stores can also select optional add-ons.
Source stores (stores that hold the inventory to be synced) are on a performance-based plan, based on the number of orders placed on connected Destination stores that include at least one product synced from the Source store, whether or not those orders are pushed. Every month starts free for the first 10 orders. More details: Source Store Plan Overview
Universal Stores pay combined billing, more information here
For more details on pricing, please visit www.syncio.co/pricing.