Piano Media, a company that powers a so-called “national paywall” used by 9 major publishers across over 40 properties in Slovakia, is set to expand into Slovenia this month, allowing customers to access content on multiple websites for a single fee.

Later this month, 9 Slovene publishers will be applying the paywall to 12 different brands and websites. Piano Media’s content payment service adds a registration bar to each participating website, forcing users to pay a fee before reading content. The Slovakian service will be charged at €1.99 ($2.53) per week, €4.89($6.23) per month or €48.90 ($62.32) per year. Subscribers get access to all participating sites when they subscribe.

From 16 January, the Piano Media bar will be added to sites to inform users of the upcoming change, with the paywall being applied from 30 January.

Piano Media launched its Slovakian ‘national paywall’ in May 2011, and says that it took €40,000 ($51,000) in its first month of operation. The Bratislava-based firm is now planning to expand its service more widely in Europe, and says that it is in negotiations with publishers in 11 countries. It plans to launch in at least three more countries this year.

Paywalls are controversial, and their superiority to advertising-funded open access to content is up for debate; we’ve heard tales of both their success and their problems. However, Piano Media’s multiple-publisher service may prove popular as long as there’s at least some synergy between the types of websites that adopt it.