Looking for a law...

[classicdrogn]

Definitely go with a lawyer to write the actual document, because just like every other legal document there's a lot of formalized terminology and formatting that may or may not be counterintuitive to the layman and getting it wrong can range from a hassle to a major difficulty to try to sort out, especially if there's anything that might be contested or otherwise open to challenge, like software companies wanting a new user to "buy" (for whatever value of the word applies with how modern EULAs are written) a new license instead of inheriting one, but doing what research you can yourself so you at least know what's reasonable to expect to be able to do, and what questions to ask to firm that up, is certainly a good idea as well, if only to not waste billable hours chasing dead ends and having them explained.