OneNote Gem Add-Ins

Question:

Isn't OneNote free?
Why does the OneNote window title appear (Unlicensed Product)?
There are also these features of the Home tab that are grayed out and not available:
 

• Paste
• Cut
• Copy
• Format Painter
• Font
• Font Size
• Bold
• Italic
• Underline
• Strikethrough
• Superscript
• Subscript
• Font Color
• Text Highlight Color
•  
• Bullets
• Numbering
• Decrease indent
• Increase indent
• Clear All Formatting
• Align
• Delete

Answer:

OneNote is free, but Office is not.
Since you have Office installed, you will need to purchase it to activate Office. Office includes Word, Excel, PowerPoint and OneNote.

If you want to only OneNote, not Word, Excel, PowerPoint. You can uninstall Office and then download the OneNote installation package from OneNote.com, and install single OneNote for free.
These features will always be available as well.
But there are no features of Word, Excel and PowerPoint in OneNote.