Can I log on as user when I am Admin?

Can I log on as user when I am Admin?

Is there a way for me to log on as a 'User'?  I am testing out some of the security and I can't figure out how to log on in 'User' mode.  So far I have just used a second email address, but I am migrating to a paid version and I don't want to pay for a user just to test.

Thanks.