If you're a devoted ClassPass member, you might be in for a bit of a shake-up. The membership service, which allows users to access classes at multiple fitness studios throughout the month, announced today that it would no longer be offering unlimited membership plans.ClassPass founder and CEO Payal Kadakia took to the ClassPass blog in a post explaining why the company would be discontinuing the unlimited option."To introduce as many people to ClassPass as we could, we tried an 'Unlimited summer' promotion in May 2014, hoping it would motivate new members to give us a try, discover boutique fitness, and perhaps fall in love with ClassPass," Kadakia wrote."For every class taken, we paid our studio partners. The more classes that were taken, the more we paid. As you can imagine, our business costs increased rapidly," she explained. "So we raised our plan prices in an effort to compensate — but we tried not to raise them too much."You might remember that ClassPass' price hike earlier this year led to some outrage from its members. "In some cities, we even had to raise our prices twice in one year, which was awful for our members and painful for my team," Kadakia continued. "We simply couldn’t make the plan work for our business.""The truth is, there is a fundamental problem with the Unlimited plan. It can’t be a long-term membership option because it doesn’t align our business with our promise."In other words, it looks like unlimited fitness classes at multiple studios ultimately is just too good to be true.As a transition, current members under the unlimited plan will keep their existing plan for 30 days before moving to the company’s "core" plan of 10 classes a month. Those members will also receive 10 free classes per month for the first three months on the new plan.Given the shake-up that ClassPass' last big change caused, we can imagine members might not be too thrilled that unlimited sessions will no longer be offered. But as Kadakia wrote, the company is setting its sights on new ventures that will hopefully soften the blow of losing such a key feature.