I've purchased a few games from there. You need to read the fine print for each game. Some are truely DRM free. Others are " DRM Free* ". I recently purchased Rayman Origins and it was of the later... That simply means the downloaded files have no DRM software on it, BUT the location/link you download the file from limits how often you can download it. For instance, to prevent abuse, I can only download the install files for Rayman Origins 3 or 4 times in a 4 week period. After that, it'll deny til the downloads are less than 4 in that time frame.
The file itself IS DRM free. It may have limitations to quantity of downloads. For any normal user, this is gonna be more than fine. You can always backup the file yourself.