You'll likely need to use ACL for that. Create a usergroup that you give to your paid users under the Access tab of your plans then create a view access level of all who should see the module then exclude your new usergroup from it. That might work for what you're wanting, but no there is no specific functionality in CBSubs to take away access by subscribing as subscribing is designed to give access. I suppose a free lifetime plan could be used to protect access to the module so only those with that plan would see it, but that won't work for public users.