Storing settings/data on microcontrollers non-volatile memory (STM32F103)
From what i know there are two options:


Use flash (emulated as EEPROM for ease of use) according to this Appnote
Use the backup registers (20 byte of battery backed registers) according to the Reference Manual Pages 67 And 79


By The Way if the you move one of the bigger brothers (F2-F4) of this chip you get a whole
part of ram battery backed something like 4k but it depends on the actual chip