Common Users

You may have to reconfigure your blogs’ database but this method has been given for doing it with two blogs. Should work with 7

Share users between two blogs
Put them both in the same database with different prefixes. Then choose one of them to be the master user table. Then do this in both wp-config.php files:

define(CUSTOM_USER_TABLE,’wp_users’);
define(CUSTOM_USER_META_TABLE,’wp_usermeta’);

Replace the wp_ with the prefix you want.

you can have multiple blogs share one database by selecting a different table prefix for each blog. They are 7 separate installations but all tables (7 blogs times 10 default tables each) will all be in one database, each set with its own prefix. The CUSTOM_USER defines to WordPress that the named tables override the default table allocation and are shared among all blogs using that database.

You will want to test this by setting up 3 or 4 blogs, either locally or on your server, in this arrangement, to confirm it will work for you, before adopting it as a solution.

Another possibility is WordPress multiuser, but that is more involved to configure and admin.

how i can use users with multi wp sites (some host and db) easy?

The above method doesn’t work, by the way. Locks me out of the wp-admin: “You don’t have sufficient permissions to view this page.”