Do i need different piwik installation for all ?
I only want to install it once and give different user logins to my customers, how can i achieve this with piwik ?
If piwik cant help me with this, then what else option do i have ?
It’s possible with a single Piwik. You can add multiple websites to one Piwik instance, you can add multiple users to it. And you can set which users can view/administer which websites.
http://piwik.org/docs/manage-users/#manage-user-access-to-websites
One thing you should keep in mind that they’ll all access Piwik through the same host in this scenario. So you might want to install Piwik on some neutral domain, eg. http://yourdomain.com/piwik instead of http://customerdomain.com/piwik.