Isn't there a 90 day/3 take-off and landings rule to keep the rating valid on your licence?
Yes, that's correct. From the Indonesian CASR (part 121);
121.439 Pilot Qualification: Recent Experience(a) No certificate holder may use any person nor may any person serve as a required pilot flight crew member, unless within the preceding 90 days, that person has made at least three takeoffs and landings in the type airplane in which that person is to serve. The takeoffs and landings required by this paragraph may be performed in a visual simulator approved under Section 121.407 to include takeoff and landing maneuvers. In addition, any person who fails to make the three required takeoffs and landings within any consecutive 90 day period must re-establish recency of experience as provided in Paragraph (b) of this section.