"Upon every remembrance of you." These words stand in the same grammatical connection with the following words, "for your fellowship," both in Slavonic and in Greek. That is, "I thank God for your remembrance," and "I thank Him for your fellowship."
Judging from this, the words should be recognized as explaining one another. Therefore, if the words "for your fellowship" point to the work of the Philippians, then "for your remembrance" should also be understood as pointing to their work.
This means that by remembrance the Apostle here does not mean his remembrance of the Philippians, but the Philippians' remembrance of him. He speaks below, in verse 7, of his own remembrance of them. Here he glorifies their remembrance of him.
The Philippians testified to their remembrance by aid sent to the Apostle. These aids were memorial offerings on their part, which also disposed the Apostle to remember them.
Since by this they assisted the work of God, and since they were moved to it by God, the Apostle thanks God for their deed. Without Him they would not have done such a deed.