Query regarding Find My Phone feature

Hello Apple support Team,

I have a question regarding the find my iPhone feature which is as follow,

- If I had set up the "find my phone" feature when I bought iPhone and didn't open at all in past 2-3 months. So does the app logout itself?

I am asking this because my phone got stolen yesterday and looking for the possibilities which could have gone wrong.

On my laptop, I am continuously seating from yesterday in front of https://www.icloud.com/#find to find the location but its not helping.

(PS: this my second time that Find My iPhone is not useful for me, I really wish Apple should lock down switching off option when phone is in passcode mode(lock mode) )

Waiting for your reply.

Thanks

Ravi