It seems like those lines of businesses correlate with one another, so they would be considered services. Per your description, those services are related to online account set up such as creating a website or website engineering because the website requires a domain name, account management, and software engineering. Because they all fall into the same category I suggest that you visit naics.com to see what business code they are suggesting for your business. Another good source is to google what job title matches the service description and going back to look through it. It is not ilegal to use the same LLC as long as the accounting is accurate and matches your records. LLC's are also allowed to have up to 5 different names under a DBA certificate which is normally issued by your register of deeds and every Schedule C form has a DBA section under the business name (you can find one example at irs.gov or in google by searching schedule-c pdf irs.gov).
Furthermore if all your services are not in relation to one another and you have no DBA to showcase all the separate services in a DBA then you have to file a different LLC per business line and then you will also have to create separate Schedule-c's for each business and have each expense separated into each business which will in turn have a separate bank account for each LLC.
I hope this helps!
