Most piano manufacturers recommend a tuning every 6 months, or at least once a year. It will depend largely on the condition of your piano, the amount you use it, and the changes in humidity.
A: Without regular tuning, a piano's strings slowly loosen with each season's change in humidity. This results in the need for extra work to get the strings back in tune. This is known as a Pitch Raise. If your piano has not been tuned for several years, there is a good chance that it has gone significantly flat. It can take several tunings before the piano re-adjusts to the correct tension and holds the correct tune. Usually, this can be done in one extended session, but it often takes more tunings before the piano will remain stable. I will let you know if your piano needs this procedure.
While I trained to regulate keys and do other minor repairs, I am currently focusing only on basic tuning. I hope to add other services as time goes on.
Just for your information.