@George > Glad you asked before you undertook the task! ;)
So long as everything is still going to be in the same locations it was before the drive swap, there will be no changes to rekordbox. Your database is in the same place, your music files are in the same place.
The key is to ensure that if you're installing Windows 10 that you use the exact same user name for your account so the path doesn't change. That said, if you use the easier method of File > Library > Backup Library and then on the new computer go File > Library > Restore Library, the system paths will be updated anyhow.
Re: the license, just remember to deactivate rekordbox before you terminate Windows 7 use.