Typically, the climbing section of the genus Lonicera is noted for being particularly greedy root feeders and can quickly starve themselves out of their containers. This process can be slowed thereby increasing their time in the pots by feeding and including some careful pruning also. Slow release organic feeds are probably best. Don't know any brand names in NZ unfortunately.

Prune out older growth that has flowered back to younger shoots at the end of the season.

The main problem in the long term is root congestion. After several years (depending on the size of the containers) the root ball will become a solid mass of roots that feeding will do very little to help though is fine early on. I would suggest keeping them in the containers until they look like their vigour is decreasing, then just plant them in the ground. At least you may get 4-5 years in their pots this way.