The Rigol DSG800-PUG is the pulse train generator licence for Rigol DSG800 series RF signal generators. Please note - This option includes option DSG800-PUM (pulse modulation and pulse generator). Each licence contains a unique product key. The product key is used to generate a software licence code that must be entered into your instrument. To generate a Rigol software licence code using your Rigol product key, please see HERE. Installed software licence codes are permanent - They are unaffected by Rigol firmware updates.