8 KB Flash and 1 KB RAM — firmware budget check
8 KB of Flash is tight. A bootloader, a communication stack (say, I²C + UART), and a state machine for a simple sensor node will fit. The 256-byte EEPROM is useful for calibration constants or fault logs that survive power loss.
The STM8L151K3U6 carries an EOL-hot lifecycle status. That means ST has announced end-of-life for this specific order code, and the last-time-buy window is either closed or closing. New production from the factory is not guaranteed.
Peripherals and integration
On-chip peripherals include a 12-bit ADC with 23 channels, multiple timers with PWM, a watchdog timer, brown-out reset, power-on reset, and a DMA controller. The internal oscillator saves an external crystal for many applications.