Can't say for sure from the pic, but it looks like it's probably a Chinese Elm, standard "mallsai" issue in standard "mallsai" soil. It's still a good time for potting in most of the northern hemiisphere, so I'd go ahead and pot it UP into a larger, non-bonsai container. It's pretty obvious that it was recently uprooted and potted and, in oredr to get it potted more quickly for sale, was not root trained. The vertical roots will need to be trained horizontal, probably starting next year, but you can already score the larger ones on repot this year and see if you can get anything out of them. DO NOT do any root pruning this year. This tree has seen enough stress. Make sure the pot you use will encompass the entire root ball, including what is already above ground, plus about 2-3" all around. Use bonsai soil, low to no compost, 50% organic (compost, pine bark, etc.) or less. Get the automatic waterer out of there. Water thoroughly, then let the soil go mostly dry before watering again. If you're worried about fertilizing, use slow release pellets. And you probably will be worried about fertilizing because you'll probably be watering with a hose, because, above all else, if I am correct and it is an Elm, it needs too be outside. There are many, many species that can be kept indoors successfully, so I'm not your typical "no trees inside" type of hardline bonsai guy. I have an extensive indoor collection, none of which are Chinese Elms of any sort. Elms, indoors, under ideal, but less than greenhouse, conditions will, almost without exclusion, die.