Clearly, hostile NPC's will not chase a player character indefinitely.  However, the precise rules as to when pursuit is abandoned are unclear.  Variables may or may not include: 

• Number of NPC's engaging player character, i.e. two NPC's may chase further than one alone.
• Proximity to player character, i.e. an NPC might pursue further as long as it is within striking range.
• Pathing and geometry.