In accordance with the Law of St. Petersburg dated June 28, 2023 No. 419-81 “On the introduction of a resort fee on the territory of St. Petersburg,” a resort fee will be collected in St. Petersburg from April 1, 2024.
Persons over 18 years of age who plan to stay at the property for more than 24 hours are required to pay a resort fee upon check-in
in the amount of 100 rubles per day per person.
21 preferential categories of citizens are exempt from paying resort fees.
If there is a benefit, residents must have with them the original document confirming the availability of the benefit, or a duly certified copy of it.

More detailed conditions can be found on the website of the Committee for Tourism Development in St. Petersburg
https://www.gov.spb.ru/gov/otrasl/c_tourism/kurortnyj-sbor/