File "c:\program files (x86)\arcgis\desktop10.7\arcpy\arcpy\analysis.py", line 1281, in Frequency
ExecuteError: Failed to execute. Parameters are not valid.
ERROR 000824: The tool is not licensed.
Failed to execute (Frequency).
Calculation of the number of observations assigned to an EO to determine if the EO fields should automatically be updated (count = 1) or requires user input (count > 1) requires the Analysis toolbox.
The problem is found on line 111:
Frequency_EOIDs = arcpy.Frequency_analysis(EO_ID, frequency_table, "EO_ID", "")
The Analysis tool is available with the Basic license in ArcPro but the Advanced license is required in 10.3 and 10.7.
Run the ArcPro version of the Observations toolbox instead to avoid licensing issues.