Yes, you ay your fees whether you choose to live in the unit or not, use it once a week or every day. Let someone else live there or decide to sell, re-decorate or go on holiday. Critical services like buildings insurance require payment through service fees. You will be required to pay any outstanding fees at the point of or prior to the point of sale and most likely with interest if you decided not to pay them on time. Failure to pay will most likely result in you being unable to sell your unit. A new owner will be most likely unwilling to take on your debt and any solicitor worth their salt will insist on it.