We haven't found a need to track too explicitly as yet. Rather we use APs as a way to have structured conversations about capacity and where effort (attention) needs to go.
I am somewhat against keeping timesheets (for many reasons) so would be cautious about tracking APs as it may lead back to some of the same thinking that the mindset of working for time brings.
The only step we have taken in this direction is allowing (through a policy) the Delivery circle to self-allocate more APs based on work projected in our pipeline. We have a simple "Hiring Trigger" policy that triggers our hiring process if the allocated APs exceed the circle's actual capacity. At the moment each delivery team simply keeps a spreadsheet of allocated APs for each role and actual by person in role. I am writing a simple app that we will trial to track total APs for a person energising roles across circles (i.e. working outside a Delivery team).