I was emailed from Gog about Pillars Of Eternity being on sale for 17.99 but now it has gone up to 44.99. The end of the email said the sale was good until 5/29/18 at 4 pm, so that's still a day away. What gives?

The Role-Playing Sale will last until May 28, 1 PM UTC.

I imagine it depends on the time zone being used. Considering that GOG is located in Poland (where it's nearly 6 AM right now) it is 5/29 for them.

I'm the west coast of Canada, so for me it's always tricky to coordinate the time. I'm used to Steam where they use PST (but that's because Valve is located in Washington State).

That was bad communication on the part of GOG.

The e-mail told you some of the highlights of what is on sale right now and told you when the weekly sale will run out.

What it failed to mention is that there where three sales running. Additionally to the typical weekly sale there were two special sales: The RPG Week and the Lots of Space sale.

And these two special sales both ended on Sunday, at 1pm and 10pm. Since Pillars of Eternity was part of the RPG Week sale you are about 17 hours late to the party.

Oops. That means that my plan to check the new Weekly Sale before buying something from RPG Sale is not so great...