Hey @Bibek
Thank you so much for reaching out to the Klaviyo Community!
The plan you are on will impact your ability to send from a flow only if you run out of email or SMS messages on your plan. However, you can Enable auto-upgrades in your account to make sure that this does not happen if you have a higher than normal need to send.
Hope this article helps! Thank you again for being part of the Klaviyo Community!