Some years ago when I made a brief foray into the software business, a big overseas client ordered our top-of-the-range enterprise software suite. I had a strategy / troubleshooting role and one day the CEO said; Drew, we have one of those 'strategic' situations you enjoy so much.
The idiot sales manager (whom he promptly fired), ecstatic with having landed a mega-deal, had omitted to send over our standard terms & conditions. The client, however, had thoughtfully appended their own standard terms to the order and, our having allowed a month to lapse and already having started the implementation, they pointed out to us that under their Civil Code, we were bound by that contract. I knew enough of the relevant law to be sure this was indeed the case.
Of course, their terms didn't at all suit our requirements (not least for revenue recognition). We had only one immediate source of leverage - otherwise they wouldn't have bothered to talk to us at all - viz that their contract didn't suit them ideally, either. It was manifestly a cut-and-paste turbine purchase agreement, with 'the turbine' tippexed out and 'the software' typed in its place. It talked about the need for fireproof clothing for workers operating in the vicinity of the fuelling system etc etc; and the testing regime too was a complete nonsense in context.
Hence, we were summonsed to the negotiating table; but the overall weakness of our position was made very clear.
So, as we were leaving, I took our onsite team to one side and told them quietly to install a dongle. A week or so later when the clients' staff booted up in the morning, a message appeared on their screens: This software is made available under a temporary licence that will expire at midnight on 31st, after which the system will become inoperable.
At our next negotiating session (some time before 31st) this matter was raised by the other side, as casually as they could contrive - and they weren't very good actors, the puddles of pee were there on the floor for all to see. Oh, I said, don't worry about that - I'll have the lads put a one-month extension on it.
And I never mentioned it again. Didn't need to, really. We got a fairly satisfactory deal, eventually.
Now, about that Brexit thing. How about the next time the Irish gas and electricity grid operators import a big, vital slug of UK energy, something pops up on their screens ...