Hey @Ekta Poddar -- thanks for your post, and great question! 

Purchasing Calendly subscriptions for your organization is like purchasing desk chairs. Once someone joins your organization, you purchase a desk chair for them. When that person leaves, you have an extra desk chair to use or to get rid of. At Calendly, we refer to these desk chairs as paid seats. 
 
When you add a new user to your organization's Calendly account, you automatically purchase a paid seat on the account. The new user will receive an email invitation to join your account, and they'll get their own account and Calendly page, along with whichever event types you assign to their account. You'll also be able to include them in team scheduling.
 
If you remove a user, their paid seat remains. That way, you can invite a new user to your organization without needing to purchase an additional seat. If you do not plan on inviting another user, you will want to remove the remaining paid seat from your Billing page.

TL;DR -- a “paid seat” is a spot in your Calendly organization that you can fill with a user. You can remove that user and invite another to fill the same seat. 

I hope this helps! Let me know if you have any more questions -- I am here for them!

p.s. check out our New User Guide - it’s full of tips + tricks as you learn the ropes!