MyChat Client Portable doesn't require the installation and usually runs from an USB flash drive. The program stores all the data in the same folder.
1.Exit from MyChat Client (Alt+X).
2.Download the latest version of MyChat Client Portable on the official website.
3.Extract ZIP-archive into MyChat Client Portable folder and rewrite all files over the old version.
4.Launch mcclient.exe.
After a short automatic database update you can use the latest version. All your settings and conversation history remains at the same place.