The program will track the images and media files that you used on your project from the folder in which you loaded them, When you reopen the project, the program will track those files from the same folder. If those were moved you would get a message to resolve and reload the images.
To avoid this, it is very simple, to create a portable project. This would keep all the media files and projects in the same folder.
To do this, select File -> Back Up Project Files to Folder, or Save Portable Project As. This will save a new copy of the project (.vpj) file in the selected folder, and all media files used in the project will also be copied into the same folder. This entire folder can then be saved to backup media, or copied or moved to another computer.