Valve has implemented a new limit on how often Steam users can change their account's country in an attempt to crack down on customers who manipulate their professed location in pursuit of cheaper games.
For several years now Steam has offered games at different prices depending on the region. Brazil, Russia, India and Argentina in particular seem to benefit from reduced prices, per a January study by VPNPro. The reasons behind the different prices are somewhat arcane, with exchange rates reportedly representing only one factor in the differences.
Reasons for the price disparity aside, wily gamers have taken advantage of those price disparities by manipulating their listed region to buy games at cheaper prices from other regions.
Changing the region of one's account is one of the most straightforward ways to get access to reduced regional prices. Now, Steam users can only change their region once every three months. Additionally, purchases can only be completed using a payment method from a user's current region.
Although Valve didn't say as much, it's likely these changes were motivated by a desire to stop players from buying games for cheaper than they should.