Method to upgrade a Trusted Application in an Execution Environment compliant to a Trusted Execution Environment standard to an as-a-server functioning, said standard defining at least one of the following locks preventing the Trusted Application in a Trusted Execution Environment to function as-a-server: a Customer Application having a session opened in an instance of a Trusted Application enters in a blocking state immediately after having sent a Command (Ci) to the Trusted Application and while the Trusted Application's Task has not finished, a Trusted Application cannot partially execute a Task, an execution context of a Trusted Application is deleted between an executed Task and a subsequent command in an opened instance/session, a Trusted Application has to be Single Instance/Multi Session or Multi Instance/Single Session, said method 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 (SPi) a session of a Single Instance/Multi Session Trusted-Pipe Trusted Application, the single session of each of the instances of the Trusted-Server Trusted Application being adapted to perform a task as a server, while said Trusted-Pipe Trusted Application being further polled (GPi) by the Customer Application and opening session depending on command coming from the Customer Application, this polling mechanism making said Trusted-Pipe Trusted Application functioning as a mailbox for said Customer Application and said Trusted-Server Trusted Application to exchange data asynchronously, while accomplishing their respective tasks without blocking each other and enabling the Trusted-Server Trusted Application to request data within its currently executing task without stopping it. a Customer Application having a session opened in an instance of a Trusted Application enters in a blocking state immediately after having sent a Command (Ci) to the Trusted Application and while the Trusted Application's Task has not finished, a Trusted Application cannot partially execute a Task, an execution context of a Trusted Application is deleted between an executed Task and a subsequent command in an opened instance/session, a Trusted Application has to be Single Instance/Multi Session or Multi Instance/Single Session, said method 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 (SPi) a session of a Single Instance/Multi Session Trusted-Pipe Trusted Application, the single session of each of the instances of the Trusted-Server Trusted Application being adapted to perform a task as a server, while said Trusted-Pipe Trusted Application being further polled (GPi) by the Customer Application and opening session depending on command coming from the Customer Application, this polling mechanism making said Trusted-Pipe Trusted Application functioning as a mailbox for said Customer Application and said Trusted-Server Trusted Application to exchange data asynchronously, while accomplishing their respective tasks without blocking each other and enabling the Trusted-Server Trusted Application to request data within its currently executing task without stopping it.