@sandeep: Assuming your question is more about WordPress plugin development than Icegram itself.
www.remarpro.com has started showing “Active Installs” of a plugin. They track plugin usage – because they get auto update requests from all WP powered sites.
If your plugin is hosted at www.remarpro.com (like Icegram), there is no way for you to track which sites are using it.
You may ask your users to subscribe to a newsletter or put a referral link and then track some statistics on your side to understand who’s using your plugin. But you can’t force them to do this.
If you sell / distribute plugins from your own site, you can override the WordPress update process to send automatic update checks to your server. And then you can get a better grip on who’s using your plugin. A lot of plugins do this – WooCommerce, ThemeForest and even ourselves (for Store Apps’s premium plugins) do this. You can even use serial keys to validate users.
Hope this helps.