String memories ... lost and regained

We discuss stringy ${\alpha'}$ corrections to the gravitational wave signal generated in merging of two black holes. model with BPS compact massive objects heterotic string, described by standard vertex operators or coherent states. Despite expected cubic suppression w.r.t. General Relativity result, at tree level string seem leave a footprint memory on signals within sensitivity region aLIGO/VIRGO and future interferometers. Including loop effects that broaden destabilise resonances suggests sort lost effect can be regained through analysis quasi normal modes ring-down phase.