Purport

Starting from this Shloka to Shloka#10, Bhagvan Shri Krishna answers one of the questions asked in Shloka#2. Arjuna asked “how a self-controlled devotee can know Him (Shri Krishna) at the time of death”
Bhagvan Shri Krishna says anybody who worships Me whole life and all the time will also remember Me at the time of death out of his very obvious habit. One who has practiced my devotion for whole life will not deviate at the tough time of death.

This way Bhagvan Shri Krishna made it clear that devotion is subject to continuous practice like other habits. Those who never worshipped or are not habituated to mediate upon Shri Krishna will find it very difficult to remember him at the time of death because the moments of death are a difficult moment for even bravest of person. At that moment the human mind is taken over fear, anxiety, and thoughts of whole life. Therefore one should meditate upon Shri Krishna regularly to be sure he is going to achieve Moksha.