You'd have to have current member area access (don't buy a new license, renew your old one), upgrade to the latest version of what you're currently using (if UBB.Classic v6 upgrade to 6.7.3, if UBB.Threads v6 upgrade to UBB.Threads 6.5.5) then install a copy of v7 in a separate directory up until the "create an admin user" step then run the importer script from your version.

The process is quite long (especially on larger forums) and you may (and likely will on larger forums) experience hiccups.

You can also hire the job out, there are several of us who preform upgrade services.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
Do you need Forum Install or Upgrade Services?
Forums: A Gardeners Forum, Scouters World
UBB.threads: UBBWiki, UBB Styles, UBB.Sitemaps
Longtime Supporter & Resident Post-A-Holic
VNC Web Services: Code Modifications, Upgrades, Styling, Coding Services, Disaster Recovery, and more!