Network slicing, i.e. multiple virtual networks running on a common infrastructure, is considered a key mechanism to serve the multitude of tenants (e.g. vertical industries) targeted by forthcoming fifth generation (5G) systems, in a flexible and cost-efficient manner. It is predicted that one of the most popular models for customers will be the Network Slice as a Service (NSaaS) model. This model allows a Network Service Customer to order and configure a Network Slice and offered it as a service. However, ensuring that the agreed SLA for the delivered Network Slice is fulfilled, monitoring and telemetry mechanisms need to be enabled at various resource levels: the Programmable Infrastructure, the 5G Core and RAN and the resources of the NS. This work presents an approach to deliver such monitoring and telemetry mechanisms as a service for the emerging 5G NSaaS delivery model.