It sounds unnatural and awkward. A native speaker wouldn't say this. It sounds better to say "I am deeply grateful for you" or "I am grateful for all the help that you gave me in the past."

I understand this sentence but the meaning might not be exactly correct. Gratitude implies thankfulness, thankful as a feeling about a gift given. I think of gratitude as a poor person would be grateful for being given a generous monetary gift. If you are remembering the person with fondness, this is not quite gratitude. You can appreciate loving care, good advice, or tender encouragement. "Appreciate" is a more deep, feeling of kindness. Using gratitude is OK but maybe you could add more explanation. You are the one I remember with gratitude for all the good advice and and friendship over the past year. or I deeply appreciate you as you are the one I remember with such gratitude for all the support you have given me. or It is with deep gratitude and sincere appreciation that I will always remember you.