Q:

Get user access token from user_id (app already authorized)

I have a poll app running on facebook (each user gets a vote each day).  Until now I didn't store on my database the user access token.  This is now updated and I'm keeping the access token by this time.  Each time a user votes I save his access token. 
My problem is how to get the user's access token from previous votes, is this possible considering that they have authorized my app?  Is there a method for this?  I have the users id.
(the only reason for needing this is to get the "is_verified" property from FB graph API)
Thanks for your help,
Hugo

A:

You cannot get user access_token without authenticate him. 
You can however send your users app to user request engaging user to visit your application so you'll be able to store user's access_token. 
Beware that access_token may expire and offline_access permission is deprecated (and will be removed soon), you can extend tokens up to 60 days (extending will only works for users who re-authenticated, not already authenticated)...

