One of the critical components of the pharmaceutical industry is the capacity of pharmaceutical forms to remain stable over time and maintain their quality under different storage and transportation circumstances. Therefore, the amount of active components in the pharmaceutical form is evaluated following the ICHQ1A standards of the European Pharmacopoeia to ascertain the validity of the pharmaceutical product. This paper aims to investigate the stability of 100 mg ketoprofen tablets. Short-term stability experiments were conducted under accelerated conditions (6 months) at 40 ± 2 °C and 75 ± 5% relative humidity, while long-term stability studies (36 months) were conducted at 25 ± 2 °C and 60 ± 5% relative humidity. Using high-performance liquid chromatography, the amount of ketoprofen released from the 100 mg ketoprofen pills was ascertained. These investigations showed that 100 mg ketoprofen tablets have a shelf life of three years and after 36 months, the ketoprofen content of the tablets was more than 95%.