I am not sure if the Pro is available via the Win7 upgrade followed by Win10 upgrade.
If you're going from Vista Home to Windows 10 Pro, you can go the following routes:
(1) directly to Windows 10 Pro, clean install, about $179 for OEM disc
(2) purchase Windows 7 Pro. clean install, free upgrade to 10 Pro, also about $179 for OEM disc
(3) purchase Windows 7 Pro "Upgrade" CD, if they're still available, upgrade Vista to 7 Pro and then free upgrade to 10 Pro. Price unknown.
(4) purchase a Windows 7 "Home" CD, free upgrade to 10 Home, and then purchase an additional Windows 10 "Pro Pack". You're looking at about $100 for 7 Home, and $139 for the Pro Pack.
The recommended route would be to get a Windows 7 Pro "OEM" CD, do a clean install, and upgrade from there before July. The Pro Pack just isn't worth it.