If you represent a non-EU company and you are based in the UK, you will no longer be able to act as an only representative after the end of the transition period, unless you relocate to an EU-27 or EEA country. Otherwise, to remain legally on the EU market, the non-EU manufacturer that appointed you will need to find a new only representative, based in one of the EU-27 or EEA countries. The registrations will have to be transferred to that new only representative.