Definition: to recall or make an effort to keep a person, event or thing in one's mind.
REMEMBER originally came from KNOW+CONTINUE which became assimilated into one sign REMEMBER.
The old ASL word "REMEMBER" signed by George Veditz in his 1913 film, "The Preservation of American Sign Language", shows two handshapes in this ASL sign. Today, there is only one handshape. This process is called anticipatory assimilation.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.