Some thing like:
actor -> target
giver -> receiver
subject -> object

Obligatee -> Obligator - ugly words, but the meaning fits perfectly

Does obligator actually mean what we need it to mean?

obligatee (plural obligatees). A person who is obligated by law to do something

that's is OK for the party on whom there is a duty

obligator (plural obligators) (law) One who establishes an obligation under law

that reads like it's the person setting the obligation rather than the target of the action carried out as part of the obligation

Licensor-> Licensee

It's clumsy but how about:

Requiring Party -> Responsible Party

Three worked examples:

Actor/Receiver
Usage notification example

1. The actor must notify the receiver when they first use the data

Audit example (roles swap between steps)

1. The actor must notify the receiver of their desire to audit data usage.

2. The actor must consent to the receiver's audit of their data usage within 30 days.

Subject/Object
Usage notification example

1. The subject of the duty must notify the object of the duty when they first use the data

Audit example (roles swap between steps)

1. The subject of the duty must notify the object of the duty of their desire to audit data usage.

2. The subject of the duty must consent to the object of the duty's audit of their data usage within 30 days.

Promisor/Promisee
Usage notification example

1. The promisor must notify the promisee when they first use the data

Audit example (roles swap between steps)

1. The promisor must notify the promisee of their desire to audit data usage.

2. The promisor must consent to the promisee's audit of their data usage within 30 days.