Formal or literary expression used in polite correspondence and speeches to express ongoing gratitude or patronage. Often appears in set phrases like 平素よりお世話になっております.
We would like to express our sincere gratitude for your continued patronage.
Thank you very much for always using our products.
Composed of 平素 (へいそ, 'usual, ordinary') and the particle より ('from'). The phrase literally means 'from the usual' and has developed into a fixed formal expression meaning 'always' or 'ordinarily'.