We are using virtual servers. Spotlight has no way of knowing that these virtual servers are not physical servers, so the key only allows connection to one virtual servers. The licensed number of servers exceeded message is displayed.
The license has a connection limit of 1, which means it will allow connections to as many instances as you want, but only on the same server. Spotlight has no way of knowing that your virtual servers are actually the same physical server.
This issue can be resolved by upgrading to Spotlight on Oracle 4.5.1