I'm not sure what transmission is in your Audi (ZF?) but personally I don't believe in "lifetime" transmission fluid. My BMW 740iL has a ZF transmission and based on the Owner's Manual and BMW dealership the fluid "never" needs to be changed. My understanding, however, is that on newer BMWs the "lifetime" has been changed to a service interval of 100,000 miles.
On the BMW 7-Series internet owner's forum that I belong to, the "lifetime" transmission fluid claim has been extensively debated. The consensus seems to be that if you see lifetime as longer than 100,000 miles it's prudent to change the fluid and filter.
My transmission had a leaking input shaft seal, and at around 50,000 miles I had it replaced and asked the transmission shop to change the fluid and filter as well. The shop I used is a highly-regarded independent shop that has been owner-operated for over 20 years. The owner is very familiar with ZF transmissions and said he loves the "lifetime" fluid claims because it's good for his business--repairing transmissions. His opinion was that 100,000 miles is the maximum for a lifetime fluid and recommends changing it well before that. I had already told him to change mine before this discussion, so it wasn't like he was trying to sell me on the change.