How long can Tresiba 100 units/mL Penfill (insulin degludec) be stored after first opening or when carried as a spare?

After first opening or when carried as a spare, Tresiba 100 units/mL Penfill (insulin degludec) may be stored for a maximum of 8 weeks at no more than 30°C, without refrigeration, with cartridges kept in the outer carton to protect from light.