Don't ever apologise for asking a perfectly reasonable question!
Just to elaborate on your point about entering controlled airspace: if you've requested a zone entry and ATC have cleared you in, it's up to them to inform you when the service changes. For example, you might be happily trundling along under a Basic service and ask for a Class D zone transit...assuming ATC have you identified, when you hit the zone boundary they should let you know they've upgraded you to a Radar Control Service, which just effectively means they have a bit more control over what you do inside CAS. Likewise when you leave, it's up to ATC to tell you they're downgrading the service, although at this point they might ask you what service you'd like outside CAS.