Your piano should be tuned at least once a year, better even twice a year. A piano’s tuning stability is especially affected by changes in humidity and temperature.
By keeping your piano in tune you not only refine your hearing, but also extend the life of your instrument.
It’s so much more enjoyable practicing on a beautifully tuned piano with a precise action – one that reacts to all the subtleties of touch and expression. Ask your piano tuner to do some minor repairs and improvements in addition to tuning the piano. You can find some tips here.