@Stateless in CDI project

Person, I have the following structure in my project (CDI):

BEAN:

@Named
@SessionScoped
public class ClienteMB extends BaseAbstractMB<Cliente, ClienteDTO> implements Serializable {

    @Inject
    private ClienteService clienteService;

    // METODOS
}

Service (interface):

public interface ClienteService extends BaseService<Cliente, ClienteDTO>{
// METODOS
}

ServiceImpl:

@Transactional(rollbackOn = Exception.class)
public class ClienteServiceImpl extends BaseAbstractServiceImpl<Cliente, ClienteDTO> implements ClienteService {
// METODOS
}

So far, this structure is correct, right? But in another project I work with in the ClientServiceImpl class we have an annotation called @Stateless (Concept: No record of all previous interactions are saved)

My question is, do I really need to have the @Stateless annotation? If so, what is its real usefulness? Because once the project is CDI, the @Stateless annotation is EJB, right? And why in a project I do not use annotation and other usage, and both function normally.

According to a colleague of mine, if I do not have the @Stateless annotation I would not be able to make a @Inject , but in the project I do not use @Stateless I can%

Does anyone know how to explain this?