There are no contracts, you can uninstall the app any time.
If you decide that Shopify Marketplace Connect doesn't suit your needs you can cancel in Shopify, or email firstname.lastname@example.org
Simply go to settings > apps and sales channels > select app > uninstall
We never end any listings when you cancel, they are just not kept in sync any longer.
Billing is by period, part periods are not refundable.
For further assistance, please reach out to email@example.com