The isLicensed method is an optional validation method that checks if a tool in a Python toolbox is licensed to execute. It can be used to restrict the tool from being run if the appropriate licenses and extensions required to run other geoprocessing tools used by the Python toolbox tool are not available.
If the isLicensed method returns False, the tool cannot be run. If the method returns True or the method is not used, the tool can be run.
def isLicensed(self): """Allow the tool to run, only if the ArcGIS 3D Analyst extension is available.""" try: if arcpy.CheckExtension("3D") != "Available": raise Exception except Exception: return False # The tool cannot be run return True # The tool can be run