In DHCP, subnets configured as scopes are counted for licensing. For example, if the customer has 10.4.1.0/24 and 10.4.2.0/24 configured as scopes, the customer will require two DHCP licenses.
Regarding DNS zone licensing, if the customer has a forward zone mycompany.com and reverse zones 2.4.10.in-addr.arpa and 1.4.10.in-addr.arpa, then three DNS zone licenses are required.
If the reverse zone is configured at a higher level, such as 4.10.in-addr.arpa or 10.in-addr.arpa, then only two DNS zone licenses are required, one for the forward zone and one for the reverse zone.