You can monitor tags from reporting section: from real time section, operator stats or custom reports. In operator stats you can check which tags have been added to a certain conversation, whereas from custom reports you will also get a summary of total tag usage within the selected time period. In the real time report you will see a summary of tags for the day.
Start by going to reports section, then select either:
Operator stats
-chat statistics
-select a chat agent whose chats you wish to view
-chats on the list with 
contain at least one tag
-click on the timestamp of a conversation to see the tags added to that chat.
OR
Custom reports:
-select chat logs (under "Available reports"-menu)
-select tags (under "Choose fields to export"-menu)
