The most important thing is to keep your roller skis clean and dry. Wash your skis after use and let them dry in a well-heated room, preferably on a floor with underfloor heating. The roller skis should be stored in a dry and room temperature place between trips.
Swenor ball bearings are sealed ball bearings. Do not use sprays such as WD40 and 5-56 as these will drive the grease out of the bearings.
Exception: Ceramic ball bearings must be both washed and oiled. Multispray such as WD40 and 5-56, or alternatively a few drops of bicycle oil, can be used here.
Go over and check that nuts and screws are tight.
Retighten if necessary.