Currently we have 3 packages available for OptimizePress:
Core = 3 Site Licenses
Publisher = 10 Site Licenses
Pro = 30 Site Licenses
We count one "site" as one installation of OptimizePress & WordPress. So if you have a separate subdomain or subdirectory installation of WordPress on the same domain as an already licensed site, you WILL need a new API key/license for that new site (it is treated separately).
For each OptimizePress site that you license and create, you can create an unlimited number of pages within that site - we do not limit this at all. The only limitation on this is the bandwidth or webspace provided by your hosting company.
Remember that as with all OptimizePress licenses, these sites must be owned, run and registered to the licensed account holder. They should not be used for client or customer websites.