'Ablösebetrag' sehe ich (in erster Näherung) wie 'Ablösesumme':

related discussion: Ablösesumme - #3 . . .

... und 'Löschung' wie 'Auflassung'

Dictionary: Auflassung . . .

Thanks, Daddy - the first is helpful, but I'm skeptical of the second -- but in checking it out, I found the on-line Enlish translation of the BGB. They say "conveyance" for "Auflassung".

Der Notar wird mit der Einholung der erforderlichen Löschungsunterlagen beauftragt. Sofern Löschungsunterlagen mit einer Treuhandauflage des Gläubigers übersandt werden, soll der Notar den für den Gebrauch der Löschungsunterlagen erforderlichen Ablösebetrag für die Vertragsbeteiligten erfragen und diesen mitteilen.

If the cancelation documents are sent with a request for payment of a trust administration fee to the creditor, the notary shall inquire as to the amount required to discharge the debt to enable use of the cancellation documents, and inform the contracting parties accordingly.

*bump*
Just trying again.
Daddy, here's why I don't think "Löschung" is "Auflassung" (the following is from the passages just preceding the sentence in the OP):

Der Kaufpreis ... zur Zahlung fällig, nachdem den Vertragsteilen die Mitteilung des Notars zugegangen ist, dass:
-...
-die Löschungsunterlagen für die jeweils in Abt. XX unter lfd. Nr. XX eingetragenen Grundpfandrechte dem Notar vorliegen

- Deitl/Lorenz has "cancellation" for lots of "Löschung-" entries that have to do with the same stuff (land register entries).

... have a look at what LEO says under 'Weitere Treffer' - There are a bunch of possibilities
(your choice included, even prevailing) . . .

Dictionary: Löschung . . .

Thank you again, but I'm more interested at the moment in figuring out what "für den Gebrauch" means!

... I read 'für den Gebrauch' like 'für die Nutzung' . . .

... use, usage or utilization ? . . .

So, do you think this is OK?

"...to discharge the debt and enable use of the cancelation documents"

(Based on my original attempt above - I've just changed the second "to" to an "and.")

I wish it said something more like "making the ... documents valid" or whatnot, but the German says "Gebrauch," clear as day. Hmph.

... well, I'm at the boundaries of my 'legalese' - It would need a 'legal eagle' to really ok it . . .

... but do carry on with the version you have now! . . .

"Gebrauch" is a poor choice of words here, I think. "Verwendung" would fit better. Somehow "avail" crawls sluggishly to mind ...

In case it helps anyone else one day: I found this helpful - the English isn't perfect (too many commas!) but otherwise seems fairly lucid:

"Second, in the contract, payment is made dependent on the deletion of existing encumbrances.
"– If the creditor is a bank, the bank normally sends alls documents necessary for cancelling the mortgage from the register to the notary and advises the notary to make use of these documents only, if the bank receives a certain amount of money (that is the bank’s claim
still secured by the mortgage).
"[...]
"– Afterwards, the bank tells the notary, that it has received the money and that now he may use the documents to cancel the bank’s mortgage."

http://www.eui.eu/Documents/DepartmentsCentre...