do S7-SCL work as stand alone software or you must have step 7 in first place and add it ?

[ in other words if i just bought s7-scl licence can i just start programming with it and upload to PLC without step7 ]

Yes, you will also need STEP 7 programming software. You can purchase the STEP 7 Basic or TIA Portal Basic software as the license you purchased is the "add on" license. If you reply with the software part number, I can verify which STEP 7 version you will need. STEP 7 Professional and TIA Portal Professional come with SCL support as part of the package.