  We study the viscoelastic properties of highly entangled, flexible,
self-propelled polymers using Brownian dynamics simulations. Our results show
that the active motion of the polymer increases the height of the stress
plateau by orders of magnitude due to the emergence of grip forces at
entanglement points. Identifying the activity-induced energy of a single
polymer and the ratio of polymer length to self-propulsion velocity as relevant
energy and time scales, we find the stress autocorrelation functions collapse
across P\'eclet numbers. We predict that the long-time viscosity scales with
polymer length squared $\sim L^2$, in contrast to equilibrium counterparts
$\sim L^3$. These insights offer prospects for designing new materials with
activity-responsive mechanical properties.
