Q-interactive renewal pricing consists of an annual licence for each user, along with a number of subtest credits (minimum purchase order 150). Subtest credit usage is via a pre-pay method, in which you continue to estimate the total subtests you may require for the licence year and pay upfront. Any subtest credits that may have been purchased in the previous licence year and have yet to be used will roll over into the new licence year.
Some additional materials may be needed for administration (e.g. blocks, response booklets etc), check the full list.