1. Lasting forever, eternal; serving in a position or office for an indefinite time: “I remained a perpetual contact with my friend till he died last year.”
2. Continuous, blooming through every season: “His wife is in a perpetual state of depression and the doctor has put her on mild sedative medicine.”
Perpetuity , on the other hand, has the following meanings:-
1. The quality or state of lasting forever; an unlimited time; eternity: ” The Taj at Agra would carry the love of Shah Jahan for his wife in perpetuity.”
2. Payment of an annuity on an ongoing basis: “The court has declared that the wife is entitled to her husband’s pension in perpetuity.”