Be wary of downloading .exe generators from sketchy forums. Many "key gens" come bundled with more than just a 20-digit code (hello, malware).
You provide the generator with your Username and the Installation Number (found via System > Status ). Sap Ecc 6.0 Developer Key Generator
In newer systems like SAP S/4HANA , the requirement for these manual developer and object keys has been largely removed. Be wary of downloading