To cite tidyLPA in publications use:

  Rosenberg, J. M., Beymer, P. N., Anderson, D. J., Van Lissa, C. J., &
  Schmidt, J. A. (2018). tidyLPA: An R Package to Easily Carry Out
  Latent Profile Analysis (LPA) Using Open-Source or Commercial
  Software. Journal of Open Source Software, 3(30), 978,
  https://doi.org/10.21105/joss.00978

A BibTeX entry for LaTeX users is

  @Article{,
    title = {tidyLPA: An R Package to Easily Carry Out Latent Profile Analysis (LPA) Using Open-Source or Commercial Software},
    author = {Joshua M. Rosenberg and Patrick N. Beymer and Daniel J. Anderson and Caspar J. {Van Lissa} and Jennifer A. Schmidt},
    journal = {Journal of Open Source Software},
    year = {2018},
    volume = {3},
    number = {30},
    pages = {978},
    url = {https://joss.theoj.org/papers/10.21105/joss.00978},
    doi = {10.21105/joss.00978},
  }