What is the validity of free version of Mailgun

As I creadted my Mailgun account 2 days back and when I run my python code for sending the email when the temperature crosses the threshold it gives me an error saying invalid key.
I have checked my ap key and its correct. So i have doubt about the validity of Mailgun free version.Please tell me what is the validity of it. If validity is not the problem then where I might
have went wrong??

i am using mailgun for almost 15 days. can u share show me your conf file so that i can figure it out whats the problem is you are facing.

Here is the code!!!

@dheerajswaroop15 can you provide ScreenShot of your conf.py file, and the validity is for lifetime until you cancel your subscription or deactivate your account.

Here is the code… Please help

@dheerajswaroop15 screenshot of your email_conf.py file. and if you can then please share SS of your mailgun dashboard and screenshot of your error.

then go through your mailgun account is it opening or blocked.
Then check your mailgun credential in your email_conf.py file is the API key correct or not.