A portable application is a program designed to read and write its configuration settings into an accessible folder in the computerusually the folder where the portable application can be found. This makes it easier to transfer the program with the user's preferences and data between different computers.
First method: to make GEDKeeper portable just create a folder called `appdata` (for Windows) in the directory where GEDKeeper2.exe is located.
Second method: GEDKeeper has the `-homedir:path` command line option which sets the path to store the application's configuration files. You may define a relative directory, if you want to specify "the current directory" (the current for environment or for the GEDKeeper binary, etc.). If the option is not used, the "home directory" defaults to a system-dependent path (such as `%APPDATA%\GEDKeeper2`).
In the case that the subfolder `appdata` is in the programs' start folder and the command line argument `-homedir:path` is given, the priority is for the command line argument and the subfolder will be ignored.