A. This time cannot be saved. Keys cannot be enabled or disabled from code; If they will ever be used, they must exist at all times.
B. This time can be saved. You can create a key group called "Year End Report" and put each key into that one group. Before running the report and deactivated by the user afterwards, the group can be activated by the user.
C. This time can be saved. The implementer can travel to the site or use software to enable the keys in the tables when needed. This is the best solution because the system can build the keys instantaneously and it allows for billing the customer at least once a year.
D. This time can be saved. You need to create many key groups. You must create a key group for each table and put the key from that table into that one group, because keys from different tables cannot belong to the same key group. Then the groups can be activated in code.