How much memory (RAM) does a Bitcoin node use?
In addition to my answer to the question Minimal system to run a full Bitcoin node: Netbook? Raspberry Pi? etc:

I just restarted my full node and waited for it to receive a new block, which revealed that 256MB of RAM will not be enough for running a full node without memory paging/swapping:



so I would suggest you opt for RasPi Model B+ which comes with double the RAM of its A+ predecessor or you can equip your A+ with a flash storage but you should expect degraded performance in this case.