UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support "UBB 10 years" image/button question

Not an important question but I'm curious..

I see some has members here on UBBcentral has a "UBB 10 years" image/button or "UBB 15 years"
in their profile, How does that work?

I bought my UBB license in 2001 and started to post here but that was as "anonymous" I probably did not register as member.
I see then posts with my name in 2006 as "Morgan" so I must be at least over the 10 year mark.

I would be interested knowing how to add a year image to the profile, also how I could implement this within my own BritBike forum.
Our members started as early as 1996 but it reads 2001 as they moved onto the new UBB forum.

Please advice