The above illustration is from a German web site with a lot of interesting information about Klaipeda (Memel) of those days!

In the early 1200s, the Teutonic Knights (‘Order of Brothers of the German House of Saint Mary in Jerusalem’) started building a castle in the Pilsāts Land of the Curonians and named it Memelburg; later the name was shortened to Memel.
From 1252-1923 and from 1939–1945, the town and city was officially named Memel. Due to political changes between 1923 and 1939, both names were in official use; since 1945 the Lithuanian name of Klaipėda is used. 

The names Memelburg and Memel are found in most written sources from the 13th century onwards, while Klaipėda is found in Lithuania-related sources since the 15th century. The first time the city was mentioned as Caloypede in the letter of Vytautas in 1413, for the second time in the negotiation documents of 1420 as Klawppeda, and for the third time in the Treaty of Melno of 1422 as Cleupeda. According to Samogitian folk etymology, the name Klaipėda refers to the boggy terrain of the town (klaidyti=obstruct and pėda=foot). Most likely the name is of Curonian origin and means “even ground”: „klais/ klait“ (flat, open, free) und “ped“ (sole of the foot, ground).

Read more at: http://www.bork-on-line.de/Memel/index.htm