Determining the Hardware Key 
You can use the transaction SLICENSE to determine the hardware keys of all hosts for which an RFC connection is maintained. The command saplicense ‑get IBM i: saplicense '-get') is then executed on the computer in question and the result is returned.
You are in transaction SLICENSE on the Remote Hardware Key tab page.
You have administrator authorization.
In the Known Hosts table, select the host for which you want to determine the hardware key. The table lists all hosts that exist in transaction SM59 as RFC destinations.
Choose Determine.
The Determined HW Key table displays the determined hardware key together with the host name. You can now simply cut and paste the desired hardware key in the appropriate field when requesting the license key.
You are now able to request the SAP license key (see Requesting the SAP License Key).