What is the latest version of LibO? I have 7.0?

I have Libre office version 7.0. But I found in " Applications and features" on windows 10 , Modify button below the Libre office name. When I clicked on it, I got windows installer instruction to install 7.3 version of Libre office. Is it required to install it?
My second question is i installed oochem-0.1.0-alpha.oxt in Libre office for chemistry drawings, But it don’t work in Libre office. it works in open office. How can i make it working in Libre office?

That extension has not been updated in more than 10 years. There is a ticket for the LO compatibility (2013).

Seems to be dead. Extensions have slightly changed for LO, the necessary changes for this extension may be limited. But will require some investigation if you feel the courage to study its code.

Just check the libreoffice.org website for the download link to the latest version.

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In addition, please pay attention to the flavor you install. The “fresh” one (7.1) is rather new, the “still” one (7.0) is recommended for any production work.