When you find some ancestors who were members of the nobility in Austria and today they are not any more, questions will arise. This is specifically true for those who became noble in the period after 1750 and who are not members of the "old" nobility with centuries of tradition.
In the registers you may find a text like "Emperor (name) elevated him in honor of his activities of the promotion of industry and trade and his outstanding services as army supplier during the wars against the Turks on (date) with "Edler von" to Austrian nobility. Due to the fact that he has settled and has property in Galicia, he was elevated into Galician nobility by a second decree of (date)."
It is worth mentioning that Joseph II. was very critical versus the traditional nobility. So he created lots of new nobility, which was also a way to help the state treasury. Sources mention that for about 6 000 guilders you could become "Baron", for 20 000 "Graf" (count), for 500 000 "Fürst" (duke). If you add to this that Archduke Carl, when he took office as supreme commander of the army in 1801, found 154 866 unpaid invoices for army supplies ...
Between 1791 and 1820 1 177 persons became noble, of which 143 into knighthood, 205 "Freiherren", 31 counts and seven dukes. Of the ones who became noble, 32.2 % were government officials, 46.8 % officers and 9.2 % businessmen. Between 1781 and 1790 businessmen counted for 18.2 % of the ones elevated to nobility. In the “Pre-march” period, before 1848, merchants (Großhändler, property above 50 000 guilders) and bankers were 64 % of the businessmen gaining access to nobility, 52 % of the ennobled businessmen were members of minorities like protestants or Jews. If a businessman became ennobled during this period, there is a statistical probability that he purchased the title, that it was a compensation for unpaid deliveries or a reward for a successful salesman of government bonds.
In any case it was a positive transaction for the state treasury, because the simple nobilitation costed 1 075 guilders. For the title "Edler" (Sir) a surcharge of 10 % had to be paid. Knighthood costed 1 575 guilders and for 3 150 guilders more you could become "Freiherr" (Baron). These fees had to be paid per man, if you wanted to ennoble also brothers or sons. For women the fee was only half - if they married a common man, the nobility would be lost. To this had to be added the fee for the establishing the papers, the painting of the coat of arms, the registration of the coat of arms and the binding of the papers. Also the box for the imperial seal and the necessary strings had to be paid. What a good ideas by the treasurers of this time to request very low VAT (respectively its predecessor, excise taxes) and to cash in on the vanity of volunteers!
Nobility also meant privileges, for example to wear spurs. Many wanted to "make their spurs". And it was a good way to assist the careers of their children. The military academy was reserved for members of the nobility.
It is also necessary to mention that nobility was an award for merit, and it was a new idea to compensate for effort, be it professional or for charity. An officer would become noble after 30 years of service when he had participated in a war, or after 40 years of service without being in war. To obtain nobility he needed to have a conduct without fault, meaning not to fall for any temptation in the sometimes very boring army life, like gambling or alcohol. In this case nobilitation came without a fee. If he was awarded with the "Maria Theresia" cross for courage, he would also be entitled for nobility, and with the Leopold medal or the Iron Crown distinction he had chances when he made the request.
The nobility name had to be unique. If he asked the title "of ..", the location name had to be a phantasy name, because the real locations were reserved for the historical nobility. This explains names like "Elkan of Elkansberg". In the case of the Hönig merchant family (the first jew nobilitated in Austria without conversion to Christianity 1789), they became "Hönig von Hönigsberg" (honey from honey hill), his nephew "Hönig von Hönigshof", another nephew "Baron of Henikstein"
After World War One, the Austrian nobility law of April 3, 1919 abolished the nobility and forbade the use of nobility titles in public. But the merit commissions of World War One had not finished their work and Maria Theresia crosses with the right for nobility have been awarded after that. As a return to monarchy did not seem impossible, the nobility registers added new nobles. During the "Ständestaat", nobility titles were allowed again. In Germany, nobility titles became part of the family name. After World War Two, nobility titles were forbidden again in Austria. The word "von" is deleted of the name, the first part of the name remains and the second is deleted in composed names.
Note: if the ancestors were nobles, what happened often for officers and higher government officials, the nobility registers give normally very detailed information about them.