technical (noob) question: how long does trezor remember its keys if not powered up for years? ...
The seed is stored in flash memory. It does not need power and the device does not have any internal batery. The minimal data retention of flash is usualy specified as 15 years, but this is the minimum that is guaranteed for devices stored in extreme conditions (85°C). When storing in normal temperatures, it should last at least 100 years according to this study:
http://www.freescale.com/files/microcontrollers/doc/eng_bulletin/EB618.pdfthanks! indeed I could not remember any battery mentioned in the bill of materials nor did I see any on the the pic of the board. just not familiar with the flash memory properties.