I have a Pages database that contains records for products purchased through commerce. I'd like for all members to be able to view the record, but to limit viewing a custom field within the record to members who have actually purchased the item and have an active subscription.

Can anyone help me with a conditional (or other solution) to accomplish this in 4.3?

Does the purchase contain a change in (primary or secondary) member groups? That would be the best thing to do in this case and then you can just check if the member is part of the group.