Yes, you can check the Group Discount addon in our demo as well.
Regarding your second query, all our premium addons comes with initial 1 year of Subscription. This means that you can download the updates and get private support forum access till 1 year of purchase date. But after one year, you will need to renew your subscription in order to continue downloading updates and get private support forum access. But this subscription has nothing to do with the usages of the plugin to your site. You can use it in your site as long as you want it without renewing your subscription.