Woke up this morning with a purple spot on my lower lip. it does not disappear when compressed and is flat so could this be a venous lake or more likely something else? wasnt there the day before?

Probably due to recent trauma, a purpuric lesion is what it appears to be. Would just observe this for several days to see if it gradually disappears. Should it become larger and more prominent, you should see your dermatologist for evaluation. A venous lake would tend to disappear when compressed.

It may be due rupture of a small blood vessel. You can watch and wait. If you get more spots, ulcers, or fever, it would be prudent to see a doctor.