Meeting SDK events endpoint URL and activation

I have created an Meeting SDK app to integrate with our website. which is working fine. Now i need recording of that meeting after a meeting ends. so i created a event subscription and provide an event notification endpoint url. In the documentation it is written that i have to manually validate only once Which i did validate it and then it will validate itself after every 72 hours. but i kept seeing “Validate the event notification endpoint URLs before submitting the app.” this message in my meeting sdk app and " [Rethink - Event Notification Endpoint URL needs validation]" this mesage in SDK activation.
So there are questions Please help with this:
Validation part
how do i activate it or do i need to activate it. but it showing in manage that it is activated T
o record meetings and get those recording i should have a paid account?
SDK Activation has Add url, i need some information on that.