Your Scratch Pad data is safe and accessible.
It can be Migrated to a new Workspace, once you create an account, using the 'Cog Icon > Settings > Data > Migrate data' menu option.
Alternatively, it can be Exported from the Lightweight API Client(signed out version) using the 'Cog Icon > Settings > Data > Export data' menu options.
I'm assuming you work for Postman. I hope you know that because of this, as well as the account requirement, other REST tools are going to eat your lunch. I don't think this was a good move.
Alternatively, it can be Exported from the Lightweight API Client(signed out version) using the 'Cog Icon > Settings > Data > Export data' menu options.