To update the free version download this update file into the directory or folder (normally "Appchkr") into which you originally installed the program. (Its base directory.) In the same way as for install, run the file update_chkr.cmd (Windows) or update_chkr (Linux) in that directory.
Subscribers receive the download automatically and will be prompted to allow the update. They may also download and run the update manually, as above, without waiting for the automatic download.