Summary
For script tools and stand-alone scripts (scripts run outside of an ArcGIS application), you can determine whether history logging is active using the GetLogHistory function.
Syntax
GetLogHistory ()
| Data Type | Explanation | 
| Boolean | True, if geoprocessing logging history is enabled. | 
Code sample
If geoprocessing log history is active, disable logging.
import arcpy
if arcpy.GetLogHistory():
    arcpy.SetLogHistory(False)