Dear Serenity Light,
Here is my opinion for the sentences (as written by you). I live in the United Kingdom.
�I live in this town for seven years�. Present Simple � NOT POSSIBLE.
�I live in this town (it is a fact)�. Possible.
�I am living in this town for seven years�. Present Progressive � NOT POSSIBLE.
�I am living in this town at present, (temporarily)�. Possible.
�I lived in this town for seven years, (but I don�t live here now)�. Past Simple � Possible.
�I was living in this town for seven years, (until I moved to London, so I don�t live here now)�. Past Progressive � Possible.
�I have lived in this town for seven years (and I still live here)�. Present Perfect � Possible.
�I had lived in this town for seven years�. Past Perfect - NOT POSSIBLE without more information.
�I had lived in this town for seven years (and then I married my wife)�. Possible.
�I have been living in this town for seven years (and I am still living here)�. Present Perfect Continuous - Possible.
�I will live in this town for seven years (and then I will do something different)�. Future Simple � Possible.
�I would live in this town for seven years�. Future Conditional - NOT POSSIBLE without more information.
�I would live in this town for seven years (if I had the opportunity)�. Possible
I have underlined what I think is the probable correct answer.
I hope that this helps you.
Les