As a freshman at LSU, Days averaged 5.3 points and four rebounds in 14.6 minutes per game. In his next year, he moved into the starting lineup.[6] On January 8, 2020, Days recorded 16 points and 16 rebounds in a 79–77 win over Arkansas.[7] As a sophomore, he averaged 11.1 points and 6.8 rebounds per game. Days declared for the 2020 NBA draft before withdrawing his name and returning to college.[8] On November 26, 2020, he made his junior season debut, scoring 24 points in a 94–81 victory over SIU Edwardsville.[9] Days missed one game with a sprained ankle. As a junior, he averaged 11.6 points and a team-leading 7.8 rebounds per game. Following the season, Days declared for the 2021 NBA draft.[10] However, he opted to withdraw from the draft and return to LSU.[11] Days was named to the Second Team All-SEC as a senior.[12] He averaged 13.7 points and 7.8 rebounds per game.[13]
On October 11, Days signed an Exhibit 10 deal with the Houston Rockets.[17] Six days later, his contract was converted to a two-way contract.[14] He split the 2022–23 season with the Rockets and the Rio Grande Valley Vipers of the NBA G League.[14] He played four NBA games during the season.[14]
On July 2, 2023, Days signed a second two-way contract with the Rockets.[18] He played for them in the 2023 NBA Summer League.[14] He was waived on October 23.[19]