I am getting below alert on my self hosted cal.com. May I know what does this mean? Do we need to pay for self hosted also?

I ran into this myself. You don't need to pay for Pro. In the database, go to the

users

table and set the

plan

value from 'TRIAL' to 'PRO'

you can change your accounts on self-hosted to PRO, however if you run a commercial product and want to use the enterprise