This is a fairly simple question.
Spain held Florida from 1513 to 1763 and again from 1784 to 1821. It would eventually lose this territory one final time following the Adams-Onis Treaty. Basically, Spain agreed to relinquish Florida if the United States agreed to abandon all claims on Texas.
Hypothetically, with a POD in 1783, how long can Spain hang onto the territory before being forced to relinquish it to another power? What would be required to delay the loss it?