Of course is does. Baptism, Confirmation and Holy Orders are indelible marks of the Holy Spirit. One cannot get unbaptised, for example.
But I thought that in Catholicism the Holy Spirit leaves the believer upon any mortal sin because we are no longer "in Christ" until confession. That sure sounds like an "unsealing" to me, in line with the Catholic belief that there can be no assurance in salvation. The believer can have no security, in contravention of Eph. 4:30.
No, the sealing is still there as the sinner is lead to confession. Your confusion is natural for someone who does not believe in the free will, but for a Catholic mind the seal opens up particular graces given to a baptised Christian, confirmed Christian and ordained Christian, but it does not sheld them from temptation. Which brings me to this general question, why pray Our Father at all given the understanding of Perseverance that excludes the free will?