How long will a lien on real property last in Texas?

Liens do not expire, they have to be settled to the satisfaction of the lien holder or lifted by the court because they are deemed invalid.

That's not true. Certain liens do expire, i.e., Abstracts of Judgment, Mechanic's Liens, Construction Liens, etc. all expire after a certain amount of time unless they are Renewed and Extended by the person/company filing the lien. Abstracts of Judgment, for example, expire after 10 years if not renewed. There should be Releases filed for these types of liens when they are paid in full, but that doesn't always happen.