[Fixes #13997] Fixes Custom license saved without identifier

[sijandh35]

Fixes #13997

Checklist

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[gemini-code-assist]

Code Review

This pull request introduces an automated identifier generation for the License model by overriding the save method to assign a UUID if one is missing. The review feedback suggests using the string representation of the UUID instead of the hex format to ensure consistency with other models in the project.