Cos4Cloud published a set of technological services aimed at the citizen science community, specifically citizen observatories (COs), for the first time on the EOSC Marketplace. The new services integrated cutting-edge technologies and were co-designed with end users to respond to the challenges of the COs. Among the benefits of Cos4Cloud services implementation are the optimization in the identification and validation of the observations, the notification of the use of the data to the end users, the automatic filtering of images and videos, a framework to facilitate the creation of mobile applications that make up of Do-It-Yourself sensors, to name but a few. The services available on EOSC evolved from existing developments from members of the consortium. The services were created and are maintained by SMEs and research institutions. The challenge once published on EOSC is their sustainability. To this end, the following document consolidates an overview of the sustainability of the services and their challenges in the context of the EOSC. This document also includes the sustainability plans for each of the services, where the following dimensions are stated: Delivery Model, Intellectual Property, Access Model, Financial Model, Operate (legal vehicle), Government Model, Business Model and Funding Strategies.