Can I activate the Tagrain QuickBooks Online Integration plugin again?

Can I activate the Tagrain QuickBooks Online Integration plugin again?

Yes, you can always choose to reactivate the Tagrain QuickBooks Online Integration plugin. However, there are 2 possible scenarios here.
Scenario 1: 
Your reactivation date is BEFORE the end of your current billing cycle. In this case, you just need to click the activate button on the Tagrain QuickBooks Online Integration plugin tile (if you are coming from the Plugin screen) OR put a tick on the activation checkbox on the Tagrain QuickBooks Online Integration plugin tile (if you are coming from the Manage Account section) to activate it.
Scenario 2: 
Your reactivation date is AFTER the end of your current billing cycle. In this case you will have to again subscribe to the plugin through the normal subscription process. 
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.