It is clearly a true fir, ie Abies spp. But confidently identifying conifers to species level on a single shot of the needles, when there are so many cultivars, is a bit tricky. As earlier poster says, Abies nordmanniana, Abies nordmanniana - Wikipedia, the free encyclopedia is the most commonly used true fir for cut Christmas trees. But part of the reason for that is that it is fast growing, which is not actually ideal for pot cultivation. Which makes me wonder whether it might actually be though actually be Abies koreana, Abies koreana - Wikipedia, the free encyclopedia which is slower growing, or at least slow growing forms are commonly sold in garden centres. That is what I would actually recommend you buy for a pot cultivated fir tree, although you might find other nice slow-growing conifers for pot cultivation in good plant nurseries. You can also get beautful slow-growing cultivars of pine species which are suitable for pot cultivation - for example I used to have a dwarf cultivar of Scots pine which grew to 4 feet in 8 years and a beautiful shape, but it got destroyed in our house extension.