Hello:
As i have seen many companies that want to manage their Employees internet access with an internal PPTP server connected to an internal radius server, but the Mikrotiks solution (PPTP+USERMAN) is not enough for them because USERMAN does not have any option to recharge Users profile based on daily or monthly schedule without any user interactions. (i have seen that some companies trick this by scheduling a script "reset-counters" but after sometime i have seen this script does not work well )
i think it might be a good feature to include in next USERMAN release.

http://forum.mikrotik.com/viewtopic.php ... 86#p408086