You must only pick classes that apply to the solutions you offer you, known as "use in commerce," or the services you strategy to give, recognized as "intent to use." Trademark registration is territorial in nature. Answer: An intent-to-use application can't mature to registration till a statement of use is filed with the USPTO, attesting to use of the mark in commerce. A registered trademark is valid for 10 years from the date of registration. There may well be trademarks that are not in our database that have rights more than yours.

In the United States acquiring a trademark search and relying

... […]