This plugin allows you to assign subscribers of a subscription plan to certain Virtuemart Shopper Groups when they subscribe for your subscription plan and remove them from Virtuemart Shopper Groups when their subscription expired.
To use this plugin, go to Extensions -> Plugins, find and publish Membership Pro - Virtuemart Shopper Groups plugin plugin. Then edit the subscription plan, look at Virtuemart Shopper Groups Settings tab, make necessary settings to get it works as you expected.