This paper deals with the role of intangible services regarding the risk of technological lock-in. It is based on the case of advisory services for farmers. Collective learning procedures are often considered by evolutionary economists as effective tools for policy makers. For instance, public investments in agricultural advisory services could support farmers into shifting towards more environmental friendly practices. Nevertheless, this hypothesis relies on an ideal conception of advisory services, focused mainly on their contribution to learning procedures. Using some conceptual tools of the service economics enables to show that advisory services can be themselves locked-in, due to their insertion in institutionalised balances of power. For instance, some Public-Private Partnerships with the upstream industry can reduce the contribution of the back-office investments of advisory services suppliers dedicated to the validation of knowledge about the relative performances of competing technologies.