Dive Brief:

• Microsoft announced Thursday that Windows 10 is now on more than 300 million active devices.

• While Microsoft’s goal of 1 billion Windows 10 users within the first two to three years is still a long way off, Windows 10 is already the most rapidly adopted version of Windows ever.

• However, the upcoming end of the free Windows 10 upgrade program may make it harder for Microsoft to reach its user goals.

Dive Insight:

Windows 10 is unusual in that it is the first Windows system to be offered as a "service" with regularly pushed updates and new features. The big anniversary updated due this summer will include several enhancements, Microsoft has said.

However, experts suspect that sustaining the current Windows 10 adoption rate will be a challenge after July 29, when upgrading from Windows 7 or 8 to Windows 10 will cost consumers $119.

Earlier this week, Windows 7 dipped below 50% worldwide operating system market share in April, though Windows 7 is still by far the most used operating system. Windows 7 users currently outnumber Windows 10 users by about three to one. If the free upgraded hasn’t persuaded people to leave Windows 7, it’s doubtful that paying for an upgrade will help.

But the true measure of success for Microsoft involves corporate adoption on Windows 10. Currently about three-quarters of Microsoft's enterprise customers are testing Windows 10, the company recently said. Enterprise users aren't eligible for the free upgrade anyway, so Microsoft may be betting on making up a lot of ground there once consumer adoption slows.