Upgrade to a Trusted Application in a Trusted Execution Environment compliant to a Trusted Execution Environment standard to an as-a-server functioning by running, inside the Trusted Execution Environment, each instance of a Multi Instance/Single Session Trusted-Server Trusted Application compliant to the TEE standard in an infinite state-full loop polling a session of a Single Instance/Multi Session Trusted-Pipe Trusted Application, the single session of each of the instance of the Trusted-Server Trusted Application being adapted to perform a task as a server, said Trusted-Pipe Trusted Application being further polled by the Customer Application and opening session depending on command coming from the Customer Application.