Enter stats on the top left, and the experience currently on you. Sell your experience below!, See your vita/mana change at the bottom
And as well see your vita amount and units bought (so that you can count how many times you pressed "Buy")
The Vita Units/Mana Units bought means, how many times you have to buy mana, so 5 mana units = 250 mana,
means, Buy Mana 5 times at Sunset weavers.