I am now prepared to give you all benedictions, according to your desire. I belong to the celestial world of demigods, who do not die like human beings. Therefore, although you are subject to death, your audience with me will not go in vain

Expressions researched:
"I belong to the celestial world of demigods, who do not die like human beings"

SB Canto 7

O best of the asuras, for this reason I am now prepared to give you all benedictions, according to your desire. I belong to the celestial world of demigods, who do not die like human beings. Therefore, although you are subject to death, your audience with me will not go in vain.

SB 7.3.21, Translation and Purport:

O best of the asuras, for this reason I am now prepared to give you all benedictions, according to your desire. I belong to the celestial world of demigods, who do not die like human beings. Therefore, although you are subject to death, your audience with me will not go in vain.

It appears that human beings and asuras are subject to death, whereas demigods are not. The demigods who reside with Lord Brahmā in Satyaloka go to Vaikuṇṭhaloka in their present bodily constructions at the time of the dissolution. Therefore although Hiraṇyakaśipu had undergone severe austerities, Lord Brahmā predicted that he had to die; he could not become immortal or even gain equal status with the demigods. The great austerities and penances he had performed for so many years could not give him protection from death. This was foretold by Lord Brahmā.