The original sentence is correct. One can treasure something even when one uses it.
'To treasure something' means 'to have or keep something that you love and that is extremely valuable to you'.
Please read my example sentences below.
This is the watch my grandfather gave me when I was a child.
I've been using it for over 30 years. I treasure it.
Is the last sentence 'I treasure it' meaningless because I've been using it?
Should it be something like 'I've been using it preciously'?
I would change using to wearing.
I've been wearing it for over 30 years. I treasure it.
Whether you use it or wear it, treasuring it is still meaningful.