OneNote Gem Add-Ins

Where is the ± Math Button in OneNote UWP?

I cannot find the "Math" button in my OneNote UWP in Windows 10. How do you display the "Math" button?
OneNote UWP Math Button
This feature may be a paid feature.
This feature is only available if you have login an Office 365 subscription account to OneNote UWP.

After login an Office 365 subscription ( Microsoft account or Work /school account ), and restart OneNote UWP, the "Math" button will be shown on "Draw" tab.