In recent years, Personal Data Stores (PDS) and dataspaces have emerged as approaches to enhance data sovereignty and user control over personal data. One prominent PDS technology is Solid, a protocol that promotes data interoperability and reuse by decoupling applications from data storage. To regulate access to stored resources, Solid relies on access control policies that define which actors can perform specific actions on particular resources. However, traditional access control mechanisms focus solely on the moment of access and do not consider how data is used after access is granted or whether the conditions under which access was granted continue to hold. To address these limitations, Solid environments require usage control mechanisms that extend beyond simple authorisation. Usage control enables the specification and enforcement of policies that regulate not only access but also ongoing and future use of data. This requires a policy language capable of expressing usage constraints and mechanisms for monitoring compliance with these constraints over time. The Community Solid Server (CSS), an implementation of the Solid protocol, has been extended to support the User-Managed Access (UMA) protocol, separating responsibilities between a resource server, which serves the data, and an authorisation server, which determines whether access should be granted. This thesis focuses on extending the authorisation server with monitoring capabilities that verify whether the conditions associated with granted access remain satisfied. By enabling continuous monitoring of policy conditions, the proposed approach aims to support usage control enforcement within Solid-based data ecosystems, ensuring that data usage remains compliant with the policies defined by data holders.