You now have to sign into Xbox Live every five years, or risk losing your Gamertag

Microsoft has changed some parts of its account service agreement, requiring Xbox users to sign in every five years or potentially lose their Gamertag.

The Microsoft service agreement that spans the company's various products, including Skype and Xbox, has been amended to add an interesting requirement for Xbox users.

According to the new service agreement, if you have an Xbox Gamertag associated with your Microsoft account (basically all Xbox console owners), you'll need to log in at least once every five years.

If you fail to do that, your Gamertag may be removed from the account, and released for others to use it. This should not affect your purchases, according to the agreement, just the Gamertag.

Microsoft does not say whether or not this will be applied retroactively. If it is, which is the likely option, if you haven't used your Gamertag since, say late 2011, you may want to log in just in case.

Microsoft regularly releases lapsed or inactive Gamertags back into the pool of available options, but this particular five-year rule is new, and it applies to Skype usernames as well.

See the full list of changes through this handy page, which includes gaming and non-gaming updates.