Hello,
From what I know, there is no option, currently, to purchase Fences 5 permanent license as an upgrade. However you can raise support ticket using the link below, use the "ask a question" option. Include all information details. Remember to record down the ticket number for future reference if needed. Do not raise multiple ticket, that will make your ticket back to the end of the line. Send once and wait. Ticket will be answer by the order they send in.
https://stardock.atlassian.net/servicedesk/customer/portal/4/group/13
Thanks
Basj,
Stardock Community Assistant