Is it rude to keep track of my sisters sobriety?

I have a sister who has been addicted to coke for a while. People around her have been dying from laced coke so she quit. I’m extremely proud of her, she’s gone two weeks already. I want to get a tracking app for how many days she’s gone without it and make sure it adds up when I ask her. to make sure she’s telling the truth but I feel like that’s so rude. I’ve just heard “I’ve been clean a month” so many times:( I just worry so much for her and I want to make sure she’s not doing it anymore