Hi,
Likely you have a papular scar left over by the pimple. Sometimes it may take a long while before it flattens somewhat. If it remains after 12 months, it is likely to be permanent. Papular scars on the nose can be difficult to treat.
Treatment options include leveling the scar by shave excision, electrocautery or ablative carbon dioxide lasering. Do discuss with you doctor your expectations and how the various treatment options may offer you an improved aesthetic outcome.
All the very best.