I’m using eM Client on Windows and it is still version 9.2.2307. If I do a Check for Updates, it says it is up to date.
V9.2.2307 is the latest version 9 release atm.
If you have a “lifetime upgrade” license, then you can download the latest V10.3.1524 via the release history page and install that version.
If you do update to V10, backup your current version first via “Menu / Backup” incase you need to restore for any reason. You can see when the backup is complete in Show Operations via clicking the drop-down on the right of Refresh.
If check for update does not show you v10 update, you highly probably don’t have v10 license, so you need to upgrade the license first.