There is no workaround for storing the tracks more than 30 days in the location tracking service in ArcGIS Online. However, the track point data can be exported to CSV fiiles which can be used in ArcGIS Pro and other tools to create derived datasets.
How long do you need to have the tracks stored? Do you really need it indefinitely?
What do you want to do with the data if it was stored for more than 30 days? Is it just for visualization? Analysis? Compliance?
We want to be able to use the track lines to tell us where a town street sweeper has been and storing indefinitely would be ideal. Visualization and compliance tracking that streets are being swept routinely.