I am flying from the north to Phuket with a layover at DMK.

I am flying with Lion Air and Nok Air. Can I bring liquor in my checked luggage? I have done this before, but only for international flights and never to or from Thailand.

I want to bring two 700ml bottles.

Any problems, or good to go?

For internal domestic flights, as long as the liquor was purchased in Thailand, no problems.

The liquor was purchased in Thailand, but how do I prove that? The bottles do have the sticker on the bottle if that proves it.

Also, can I carry both bottles in my luggage? Or do I need my friend to carry one.... if there is a 1 liter/person rule.

Just do it......no have customs....

Only durian is forbidden

But honestly: there is absolutely no restriction on that for domestic flights.

Forbidden are only the usual dangerous goods like explosives, gas cartridges etc. like on any flight worldwide.

From Thaiairways:

International law prohibits the placing of magnetised, inflammable, corrosive, radioactive, oxidising, or explosive articles; pressurised gasses, toxic substances, oxygen cylinders, paint, mercury, munitions, and fireworks in checked or unchecked (carry-on) luggage. In many countries, strong-smelling materials, lighter fuel and refills, fresh food or fruit, infected live animals, or weapons must not be taken aboard the aircraft. Such items are subject to confiscation and the owner may be subject to a fine, depending on the country. If you are not certain if an item you are carrying is prohibited, please ask a THAI agent before you arrive at check-in.

strong-smelling materials = durian