The Rigol DSG800-PUM is the pulse modulation and (single) pulse generator licence for Rigol DSG800 series RF signal generators.
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.