Mass Effect uses SecuROM and requires an online activation for the first time that you play it. Each copy of Mass Effect comes with a CD Key which is used for this activation and for registration here at the BioWare Community. Mass Effect does not require the DVD to be in the drive in order to play, it is only for installation.

After the first activation, SecuROM requires that it re-check with the server within ten days (in case the CD Key has become public/warez'd and gets banned). Just so that the 10 day thing doesn't become abrupt, SecuROM tries its first re-check with 5 days remaining in the 10 day window. If it can't contact the server before the 10 days are up, nothing bad happens and the game still runs. After 10 days a re-check is required before the game can run.​