If you’re planning to install Windows 10 and benefit from Microsoft’s free upgrade offer, you might want to hurry up because there are only 100 days left until the promo expires.

Microsoft launched Windows 10 on July 29, 2015, and started offering the operating system completely free of charge for those who were already running Windows 7 or 8.1. In order to make the upgrade as smooth as possible, the company is even offering the so-called “Get Windows 10” app that automatically installs on Windows 7 and 8.1 PCs, scans for compatibility issues and downloads the necessary files for the installer.

Although it’s not supposed to happen, Windows 10 was deployed on a number of PCs without users specifically requesting it. This is how applications that can block the Windows 10 upgrade, such as GWX Control Panel, became increasingly popular with users who simply wanted to stick with Windows 7 or 8.1.

What happens after the free upgrade period ends?

The biggest question right now is what happens once the free upgrade period comes to an end and users are no longer allowed to upgrade to Windows 10 free of charge.

As Myce notes, Microsoft hasn’t dropped any hints as to what could happen after that, but it’s believed that the company might actually extend the offer for a few more months or offer Windows 10 at a special price for customers already having Windows 7 and 8.1 on their devices.

Microsoft has a goal of bringing Windows 10 on 1 billion devices by 2017, and without making Windows 10 free, or at least more affordable, it’ll be a challenge to achieve this. The company said that 270 million devices already run Windows 10, and with enterprises currently piloting the OS, it hopes that this threshold will be reached very soon.

For the moment, Windows 10 continues to be available as a free upgrade, but since the clock is ticking on this offer, you should really start considering your options.