Open FL Studio, go to HELP > About , and click the "Unlock with file" button to browse for and select your saved .reg key.
There is no technical or educational “deep article” to write about flregkey.reg as a legitimate subject. The only accurate article would be a malware analysis report — and running or promoting its download would be dangerous and irresponsible. flregkey.reg file download
Alternatively, you can manually import the file via the Registry Editor (Regedit.exe). However, this method is more complex and generally not recommended unless you're familiar with editing the registry. Open FL Studio, go to HELP > About