Blazars, the most extreme class of active galactic nuclei (AGN), are characterized by strong flux variability across all wavelengths and relativistic jets pointing in Earth’s line of sight. The high-energy spectral study of blazars at the GeV-TeV range provides insight into the particle acceleration and gamma-ray emission mechanisms in blazar jets. Detailed Fermi-LAT analyses of a sample of blazars detected by VERITAS, atmospheric Cherenkov telescopes located at the Fred Lawrence Whipple Observatory, were performed to investigate the long-term gamma-ray variability of TeV blazars. A Bayesian blocks analysis was used to identify steady-flux periods for parameterization of the gamma-ray spectral cutoff. The correlation between gamma-ray hardness and flux was examined. We report on the results of flux and spectral variability of these blazars.