Why was Jackie so quick to go back to using after she got her license back?

She went through all that shit with moping floors and being a janitor and scraping and clawing the money together to afford her lawyer and barely win back the trust of her friends and family. She just went through so much shit to get back to being a nurse and she just started using again as if she was eating nothing more than tic tacs. The drugs was the reason she just went though all of that and she just started using them again like she just forgot about everything those drugs caused her to go through.

Its just so weird considering how she was clean for a year at one point and was genuinely trying to stay clean, she eventually started using again but it was after trying really hard not to. But here at the end she went back to using with no care in the world and no shame whatsoever, she started popping pills like candy again almost the second she got her license back.

I figured there would have been some scene of her trying to resist using again and thinking about how hard it was to get back to being a nurse again, but no she just started using again as if she gave no fucks about being caught or losing it all over again. She started using as if she was celebrating, and popping pills as she walked down the hallways.