The free Windows 10 upgrade period is finally almost over—but Microsoft isn't going to let Windows 7 and 8 holdouts escape without one last giant full-screen nag.

The full-screen nag will appear over the next few days for some users. The Metro-style prompt gives you four options: you can upgrade to Windows 10 immediately; ask to be nagged again three days from now; ask to be nagged three more times; or opt out of any further notifications.

The free Windows 10 upgrade offer ends on July 29, after which you'll be charged £99/€135/$119 for Windows 10 Home or £190 for Windows 10 Pro.

Not everyone will see the full-screen nag: if you've previously opted out of the Windows 10 upgrade, or disabled the offer through the registry, your preferences will be honoured. You also won't see the nag if your computer has tried and failed to install Windows 10 before, or if you've installed and then uninstalled Windows 10 previously. If you have a recent version of the "Get Windows 10" app installed, you also won't see the nag.

Microsoft's free Windows 10 upgrade offer has been put through the wringer over the last 12 months. From over-eager upgrade nags, to paying out $10,000 for an unwanted Windows 10 upgrade, to an upgrade dialogue that is won't stay closed, Microsoft has shown that there are a surprising number of pitfalls even when trying to give away software for free.