On the Integrations section of your AppScenic Account, you have LAST SYNC on the top of your online stores list.

The date and time here coincide with the last time your products were synchronized between your online store and AppScenic. 

If your store is Connected, then LAST SYNC will show the date when your store was last time synced, and that's whenever there is a product change on your online store.   

And that’s LAST SYNC!