Microsoft Windows 10 won’t be free for everyone after a prolific leaker confirmed that certain Windows 8 users and all Windows 7 customers have to pay a small fee for the update.

Read more: Why Windows 10 will be good

Russian leaker WZOR claims that it will only be free for those customers that bought a full retail version of Windows 8 and 8.1, and not for anyone that had it preinstalled on a machine or any Windows 7 users.

In terms of pricing, Myce reports WZOR as stating that an upgrade for Windows 8 OEM users will cost around $20 [£12.34] whereas those that are still on Windows 7 have to spend $30 [£18.51] to get it.

Microsoft has a launch event scheduled for 18:00 BST tonight where it will out Windows 10 as a “technical preview” that will be opened up for beta access and worked upon before the full roll-out takes place at some point next year.

The most welcome update to Windows 10 should be the return of the Start Menu after it was left out of Windows 8 to the consternation of almost all that use the OS, and early shots look similar to the Start Menu in Windows 7. A higher level of personalisation is set to be central to the OS with users able to turn the trademark tiled UI on or off at any time.

Voice assistant Cortana will also hit Windows 10 after a successful debut on Windows Phone and certain parts of the desktop OS will also be altered when it is run on Windows tablets.

Read more: Excited for Windows 10? You won’t believe how far it’s come since Windows 1.0

You can follow the Windows 10 launch on our live blog for a detailed account of just what Microsoft has up its sleeve from 18:00 BST.