The standard/free is highly functional - it supports open and commercial vpns (including personal-class equipment like Netgear router+vpn's), I'm not even sure what the Pro features enable - they describe it as "offers additional features that may be helpful for users connecting to a corporate LAN"
Mysql is fully functional/free on it's own, but there are enterprise/carrier-grade versions which are only for pay - I don't quite see the difference. (although mysql is more open to code submissions)