Your LimeSurvey account holds your survey site, your plan and your invoices, on your account page at account.limesurvey.org. Creating an account is free. An account you create with Get started - free starts on the free plan. See The free plan.
When you log in for the first time, LimeSurvey creates your survey site. See How do I set up my survey site and log in?
Note: Only one person logs in to the account page: the primary admin. Colleagues get their own users on the survey site. See Overview: The primary admin account.
The Account details tab has three blocks: Your survey site, Profile and General preferences. The tabs Billing details, Billing history and Quotes hold your billing address, your plan with its invoices, and your quotes. See Overview: Your LimeSurvey account.
Check your spam folder. If it isn't there, see Can't log in? Reset your password or recover your account.
At first, yes: your survey site uses the same username and password. After that they are separate, and the admin password of the survey site is reset on your account page.
Yes. On the pricing page, click Get Basic, Get Expert or Get Business, or upgrade later with Upgrade at the top right of your survey site. See Upgrade your plan.