Upgrading from windows 8.1 pro to windows 10 pro

Hi ,
I have just bought Toshiba portege Z20t which comes with pre-installed windows 8.1 pro and the right operating system now is windows 7 pro downgraded from window 8.1 pro ,
my question is I want to upgrade to windows 10 but to make this first I have to install the coming windows 8.1 pro DVD recovery of toshiba company on my laptop ,
Can I bypass this by direct installation of windows 10 pro from usb boot or windows 8.1 pro from usb too,
as I will need to buy an external dvd to boot from the 3 DVD recovery that came with the device.
I mean the programs that comes with the recovery dvds of windows 8 from toshiba will still be working on Windows 10 pro after upgrading ?
Or just skip the recovery and proceed with usb boot ?
Thank you

If it came with Windows 8.1 Pro from new, there's a good chance the Windows 8.1 Pro product key will be on the motherboard (and I think Windows 10 would automatically activate from that).
ShowKey should reveal all.

Thank you all , I already extracted the key of windows 8.1 pro from bios but I mean will I get any extra benefit if I installed windows 8.1 from DVD recovery using the 3 dvds came with laptop from toshiba company than I used clean installation by USB booted with windows 10 pro ?? I mean the programs or patches that come with the original DVDs is there difference ?

Most people prefer to have a clean install of Windows without all the extra stuff the manufacturer throws in. When I get a new computer, I make an image of the hard drive by booting into Macrium Reflect. Then I play with the factory software for about 10 minutes, wipe the entire hard drive and start over with a clean load of vanilla Windows downloaded from Microsoft.

Thank you all , so do you recommend certain program to make copy of all images found on my laptop SSD before I erase them ?

Sometimes there are problems upgrading. For example the free space in the partition could be insufficient. There could be incompatible software/applications that need to be uninstalled before the upgrade. The clean install of windows 10 (deleting the partitions, formating the drive, etc. eliminates these potential delays or incompatibility problems. They may never occur but most often you have to attempt the upgrade to see if there are problems.

So clean installation is better ?