Go to Service Market Place (www.service.sap.com) , Under the Tab Keys&Requests-->>SSCR Keys , there you can create Developer or Object.
Before that you need to get OSS Id to Service Market Place with privileges to create Developer Keys for your respective installations.
Pls award the points if my answers are helpful.
Please find below steps to create the OSS ID.
Login to www.service.sap.com --> Click on Data Administration ---> Under this click on User data -
> click on Request new users --> It will open the User request form enter the details --> Save ---> provide authorisations by clicking the Authorisations button at the bottom of the page.
It will take sometime to get your OSS ID.
"Award points if it is really helpful"