Microsoft improved a lot the upgrade process in Windows 10.
If you just bought a laptop with Windows 10 Home and you want to upgrade to Windows 10 Pro in order to have access to more advanced features (like the Bitlocker Drive Encryption), you need to follow just a few simple steps:
1. Go to Start / Settings
2. Go to “Update & Security”
3. Go to Activation / Change Product Key*
*In order to receive the Product Key, you have to go to the Windows Store and buy a Windows 10 PRO licence. The S/N you receive you can insert here.
4. After you insert the product Key, your Windows will prepare for the upgrade*. This is going to require a few reboots.
*All the software/files are kept on your computer! However, having a backup is always a good idea, and I recommend you to keep one either by using the a Cloud Storage solution (Google Drive, One Drive, Dropbox etc), or by keeping a backup on an external hard-drive (and constantly updating it by using different specialized software).
5. After a few reboots you will be able to use your new Windows 10 PRO.
If you have questions please drop a line in the comments section!