Quote: eHow
Passive RFID tags do not carry their own power supply; the energy they need to communicate is provided by radiation from the RFID reader. * They have no battery to run out and, as such, have a virtually unlimited life expectancy of perhaps 20 years or more. Passive RFID tags are usually attached to library books, for example, which may spend long periods of time on a shelf and be issued many times during their lifetime. Library books require RFID tags that operate reliably over and over again for years or decades.
Amazing if true (and this is not the only source which mentions it)
(Interestingly, in an interview, it was once stated that Acti would like the franchise to be a long runner for about 20 years or so as well.)
*Skylanders figurines are definitely not "Active" RFID devices. I will assume that they are Passive since LightCore figurines do not use an internal battery either and memory can still be written to Passive tags.