Abidemi Kusimo

You can make use of category popular tag to display most used tag on your blog. This will give list of frequently used tag anywhere you place the shortcode or funtion in your theme.
For example [popular_category_tags count=10 type=”popular-tags” category_id=”1″]. 
You can also call this function from your theme file: cush_category_popular_tag() for basic output.
When using the shortcode type is required. category id, count is not required. if no category id suplied, the plugin will default to current post category available. 
For example [popular_category_tags type=”popular-tags” ].
You can find category tags options under Settings page 
Settings -> Category Tags
Credit : (https://wordpress.stackexchange.com/questions/261617/display-most-popular-tags-of-category)

Category Popular Tags

Display popular tags on achieve/category page of your theme using sortcode or by calling a function.

Bill Erickson

This is a helper plugin to allow you to build WordPress queries using WordPress.com stats.
This plugin uses the WordPress.com stats (packaged in Jetpack) to find out your most popular posts. You must be running Jetpack for this plugin to work. I recommend running Jetpack for at least 30 days to get useful data.
It asks for the 100 most popular posts over the past 30 days. This includes both posts and pages, since their stats don’t let you filter based on post type. I filter this list down to just posts and then store its ranking as post meta (‘be_stats’).
You can <a href="https://gist.github.com/billerickson/4997202" rel="nofollow ugc">write custom queries</a> to list popular posts, or use the <a href="https://wordpress.org/extend/plugins/display-posts-shortcode/" rel="ugc">Display Posts Shortcode plugin</a> to do it for you. Examples using the shortcode plugin:
[display-posts orderby=”popular”] – Lists the 10 most popular posts 
[display-posts orderby=”popular” posts_per_page=”4″] – Lists the 4 most popular posts 
[display-posts orderby=”popular” posts_per_page=”4″ tag=”basic”] – Lists the 4 most popular posts tagged “basic”
<h3>For Developers</h3>
There are a few filters available to you for customization. Refer to the plugin’s code for more information.
be_stats_args – arguments passed to WordPress.com Stats API. 
Default: array( ‘days’ => 30, ‘limit’ => 100 ) 
Example: http://www.billerickson.net/code/customize-be-stats-arguments/
be_stats_update – Conditional for determining if stats data should be saved 
Default: ‘post’ == get_post_type() 
Example: http://www.billerickson.net/code/be-stats-change-ranking-conditions/

BE Stats

Keeps track of your most popular posts for display in site

Category Popular Tags vs BE Stats