GL, if an LLC member doesn't withdraw all of the profit which is allocated to such member by the profit-allocation agreement, then the portion of such profit not withdrawn is generally added to the member's capital account. It's the LLC's analog to a corporation's "retained earnings".
It isn't generally added to a "loan to company" account, unless the member explicitly withdraws it and then loans it back to the company.
Members can usually make draws from their capital accounts, but this ability can be tempered or modified by the LLC's operating agreement. Just as an example, if the members feel that it's important for the company to maintain a certain level of positive equity the OA might restrict drawdowns to a max of some X% of a member's capital over a designated time interval.
If the members' collective capital is an important income-generating component for any given business, then those members should take note of how the members' relative investments can change over time, if some members are withdrawing the capital at a greater rate than other members. Four members might start out, for example, with each having invested 25% of the firm's total capital. But that can become skewed over time if the members are not withdrawing their allocable profits at the same rate, leaving some member(s) with much more of their personal wealth invested in the company than others.