We present optical and NIR photometry and spectroscopy of SN 2013L for the first four years post-explosion .
SN 2013L was a moderately luminous ( M _ { r } = -19.0 ) Type IIn supernova ( SN ) that showed signs of strong shock interaction with the circumstellar medium ( CSM ) .
The CSM interaction was equal to or stronger to SN 1988Z for the first 200 days and is observed at all epochs after explosion .
Optical spectra revealed multi-component hydrogen lines appearing by day 33 and persisting and slowly evolving over the next few years .
By day 1509 the H \alpha emission was still strong and exhibiting multiple peaks , hinting that the CSM was in a disc or torus around the SN .
SN 2013L is part of a growing subset of SNe IIn that shows both strong CSM interaction signatures and the underlying broad lines from the SN ejecta photosphere .
The presence of a blue H \alpha emission bump and a lack of a red peak does not appear to be due to dust obscuration since an identical profile is seen in Pa \beta .
Instead this suggests a high concentration of material on the near-side of the SN or a disc inclination of roughly edge-on and hints that SN 2013L was part of a massive interactive binary system .
Narrow H \alpha P-Cygni lines that persist through the entirety of the observations measure a progenitor outflow speed of 80–130 km s ^ { -1 } , speeds normally associated with extreme red supergiants , yellow hypergiants , or luminous blue variable winds .
This progenitor scenario is also consistent with an inferred progenitor mass-loss rate of 0.3 - 8.0 \times 10 ^ { -3 } M _ { \sun } yr ^ { -1 } .