Acrobat is sold per named user, split across Pro and Standard, and increasingly pushed onto enterprise term agreements where the seat count is locked for years. Adobe prices the Pro tier well above Standard, then encourages a blanket Pro rollout so the higher tier becomes the default.
Document Cloud layers Acrobat Sign on top, billed on transaction volume or a committed envelope count. The commitment is sized for growth you may never see, and the overage rate on signatures past the commitment is where the surprise lands.
Acrobat is also a favourite bundle filler. It gets folded into a wider Creative Cloud or Experience Cloud deal so the per seat cost disappears into a blended number that nobody can challenge at renewal.