so long as

(idiomatic) Depending upon some condition or requirement; provided that; if, assuming; as long as.

Example:   I don't mind if he stays there, so long as he cleans up after himself when he's done.
1920, Herman Cyril McNeile, Bulldog Drummond Chapter 1
  Hugh helped himself to bacon. "My dear fellow, she can think what she likes so long as she continues to grill bacon like this. Your wife is a treasure, James—a pearl amongst women; and you can tell her so with my love."