There is no actual difference in the need for number of licenses between the old local on the router or having the licenses in a virtual smart account. Using Smart Licensing is actually a better option as you get to keep the licenses even if you replace the router, ie the licenses are device agnostic and you’ll also get the possibility of pooling the SIP trunk licenses across all your gateways. Apart from this there is a dead end for on hardware licenses and that will mean that you can never go past version 16.9 of IOS and that’s becoming quite old these days.
This would be the same for both options. The difference is where the licenses are housed. For both options you always should have the licenses to cater for the number of users that are to use the gateway and you’ll need to have the UC license for the router to act as a voice gateway. If you don’t have the actual number of licenses for your users you’re in violation of the license agreement.
