This is one of those cases where there are two hostas with the same name. One is registered and, therefore, the "official" version of H. 'Key Lime Pie' while the other is a non-registered plant and needs to be renamed to avoid further confusion.

Hans Hansen of Minnesota registered this sport of H. 'Squash Casserole' in 2003. Its large size mound of heavily rippled foliage reaches 23 inches high and 60 inches wide. The flowers are medium purple and bloom in July.

 

According to The Hostapedia by Mark Zilis (2009), "...the name 'Key Lime Pie' was used for  other hostas, including one from Pauline Banyai of Michigan."

The New Encyclopedia of Hostas by Diana Grenfell (2009) states: "Fast growing. Divide regularly...Differs from its parent in having yellow-margined leaves."

Hosta Helper will call this plant 'Key Lime Pie' (Hansen)
 

Originated by Ran Lydell of Cooks Nursery and Eagle Bay Gardens in New York, this medium size, non-registered cultivar is light green with a creamy yellow marginal variegation. The broadly ovate leaves are slightly corrugated and slightly convexly (downward) cupped.

Hosta Helper will call this plant 'Key Lime Pie' (Lydell)