Will the Tagrain QuickBooks Online Integration plugin deactivation affect my existing subscription?

Will the Tagrain QuickBooks Online Integration plugin deactivation affect my existing subscription?

Yes, deactivating the Tagrain QuickBooks Online Integration plugin will reduce your subscription amount for your next billing cycle. The reduction in amount will depend upon your choice of edition, number of plugin licences, and the billing cycle that you have opted for. The Cart Details on the Purchase Subscription screen clearly indicates the subscription amount from the next billing cycle. 
The Tagrain QuickBooks Online Integration plugin is not available for activation if you are running the 14-Day trial evaluation of Tagrain.
Plugins in Tagrain are either Subscription Based or License Based. So the price that you pay for your plugins is based on the number of POS terminals that you have in your setup and the number of licences that you have acquired.
There will be no change in your subscription amount in the current billing cycle if you are only deactivating the Tagrain QuickBooks Online Integration plugin AND not updating your Store / POS count.