Upgrading to a PRO account gives you a couple of benefits over the free version. While both the Premium Free and Premium PRO accounts give you access to all features, the FREE account will add delicate "Powered by Call Now Button" branding to your buttons. This is removed in the paid plans. Additionally, the PRO accounts allow for more monthly visitors. PRO allows for up to 50k monthly visitors while Free is only for websites that have less than 20k visits per month. PRO Large is suitable for websites with more than 50k monthly visits.