You could change the purpose of your LLC by filing new or amended documents with the state. But you don't really have to--there isn't any general legal import or effect to those statements of corporate (or LLC) purposes, and a business, once created, can engage in any legal course of business not specifically prohibited to it under its operating agreements or articles of incorporation. I suppose that if you have or anticipate or want investors, there is an advantage to having your company's "purpose" align with its actual actions and businss model; however, apart from that, there is no actual need to make the change you inquire about, so long as there is nothing actually prohibiting your LLC from engaging in the new endeavor.