Rose Plus is a brand created by Harmony, with a small price increase to cover the cost of relapses. If your cat experiences a relapse after treatment, the following coverage applies:
100% coverage for relapses within 84 days of ending the treatment.
50% coverage for relapses occurring from day 85 to day 180 after the treatment ends.
This means that if your cat has a relapse within the coverage periods, and you followed all the treatment requirements, your next treatment will be free if it's within the 84-day period (100% covered). After that, you'd pay half the cost (50% coverage) for the next treatment if the relapse happens between day 85 and day 180.
See requirement here to be eligible (Simply purchasing Rose not not qualify you)