The actress, 26, shared a sweet post on Instagram Saturday, marking what would have been Boyce's 23rd birthday.
Sharing a black-and-white video of herself reaching out to hold Boyce's hand while sitting beside him on a panel, Cameron began the caption of her post, writing, "Somewhere unnamed, these moments are all still occurring for the first time, for the millionth time, in real time and all at once, just as real as I remember them 'then.' "
"You are here, still. We feel you, still. I will love you, unchangingly, just like this," she continued. "Happy birthday."
Cameron's post also included what appears to be a handwritten note from the late Descendants actor of the words "Maybe heaven is a jazz club," written on lined paper.
"It is with a profoundly heavy heart that we report that this morning we lost Cameron," a family spokesperson told PEOPLE in a statement at the time.
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"He passed away in his sleep due to a seizure, which was a result of an ongoing medical condition for which he was being treated. The world is now undoubtedly without one of its brightest lights, but his spirit will live on through the kindness and compassion of all who knew and loved him," they continued.
The spokesperson added: "We are utterly heartbroken and ask for privacy during this immensely difficult time as we grieve the loss of our precious son and brother."
The Grown Ups actor's parents subsequently launched the Cameron Boyce Foundation in his memory, aiming to provide "young people artistic and creative outlets as alternatives to violence and negativity and uses resources and philanthropy for positive change in the world."
Last week, the foundation hosted its inaugural gala, Cam for a Cause: A Fundraiser for The Cameron Boyce Foundation to End Epilepsy, raising money and awareness for epilepsy and SUDEP (Sudden Unexpected Death in Epilepsy).
"Cameron would've been 23 years old this year. Just thinking about that breaks my heart, every minute of every day," Cameron's dad Victor Boyce told PEOPLE. "But, every year on his birthday, he didn't want presents. He wanted to give back and he would always do something to help others. In that spirit, that's why we're doing the gala."
His mother Libby Boyce added: "We have an obligation to use Cameron's voice. Even though physically he's not here, he would want us to do that, to bring attention to those people who are isolated and stigmatized because of their epilepsy."
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Alongside Cameron, another one of Boyce's friends and Disney Channel costars paid tribute to him on Saturday as well.
"Our Angel. Forever. I adore you my Cam," wrote Sofia Carson, sharing a throwback video of the birthday boy strumming on an acoustic guitar and singing a song. She also shared some photo and video memories on her Instagram Story.