In mortal life, I believe we experience freedom with God only through moments of creativity -- those moments in life when we are able to tap into something immeasurably deep within us and bring forth an upsurge of being that transcends the entropy, evil, and necessity inherent in the world process.
The fulfillment of tasks is a certain kind of "need to do"; creativity is another class of "need to do" altogether.
Creativity is the appearance of something that is new and original to our unique selves -- that deepest, innermost aspect of ourselves.
It is the free movement of this deep inner self attuning itself with Creation and introducing into Creation something Creation alone could not have introduced.
Once the creative movement is introduced, God takes notice and consents to freely work and co-operate with the creative impulse being introduced into Creation. In that moment, we are "free with" God. The impulse is added to Creation, becomes a part of Creation, expands and deepens Creation.
When I think of heaven, I envision it as this sort of eternal co-creation, working creatively with God and with other beings who have also chosen to freely align themselves with God in love.