If you are running on an actual PS3, the system can sometimes "repair" the game structure for you. Navigate to your game in the multiMAN list. Press Triangle for options.

For users on Custom Firmware (CFW) or PS3HEN, modern homebrew apps often bypass the need for manual generation: Apollo Save Tool:

The file is essentially a license descriptor used by the PS3 system. It resides within the PS3_GAME/LICDIR folder of a game’s directory structure. Its primary job is to tell the console (or emulator) that the game is authorized to run. Without it, many games will simply kick you back to the XMB with an error code like 80010007 . Why Would You Need to Generate One?