This is what my search on google yielded (check link), and the top search results seem quite unanimous. Agdas business seems centered on making business systems (of which "Agda lön" is (the?) one) that handle(s) personnel and wage issues.
http://www.agda.se/agdaweb/foretaget/foretagetv2.aspx

"Vårt produktnamn Agda har sitt ursprung från Allmänna Gruppen (nuvarande Almega) inom Svenskt Näringsliv och Danska Arbetsgivarföreningen."

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Note added at 1 hr (2009-04-20 23:23:43 GMT)
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I just realized that my term suggestion focuses on AGDA, not AGDA lön... Anyways, if it is a specific computer system as it seems, I'd wager it's an intranslatable which could be explained with a note, subordinate clause or the like.