Steam announced lately, that it is stopping the support for Russian accounts when it comes to transactions. These include subscriptions, any in-game transactions or simple purchases of the games available on Steam. Russian users are now unable to use any cards and payment services besides PayPal. 

In action the prompt window shows like this:

Currently, purchase using the selected payment method is not possible. We apologize for any inconvenience caused.

The restrictions are correlated to the current situation with Ukraine and Russia. Before Steam, GOG online store joined this movement too: purchases in Russian Roubles are not allowed there any more.