@Pete ******
okay, so this means you got a multi re-entry included until the expiry date of the visa validity. Attention: this expiry date is NOT the same date as the expiry date of the 1-year stay permit you got stamped in on September 1. So as long as you enter before the expiry date of the visa (that's the date behind the text "visa must be used until" on the .pdf visa document) you will get stamped in for another 365-days, which however depends on how long your health insurance is carrying you, as you will get stamped in for not any longer than the expiry of the insurcance - OR for a maximum of 365 days. AFTER the expiry of the visa validity, you do not have a multi re-entry permit any more,. This means, that if you wish to travel and exit Thailand during the "second year" you need to buy a re-entry permit in order to keep the most recent stay permit stamp alive