There are no requirements to lock up your ammunition, you have to store your firearms so they cannot be easily accessible to ammunition unless the ammo is locked up with the gun.
The rules for ammunition storage are part of the Natural Resources Canada rules, not firearms law.
Below is what is written online.
So you decide who has access but no there is no stipulation on a PAL being required.
So if you authorize everyone in your house to have access then all you need to do is lock your door when you leave.
Do not store them close to sources of ignition or flammable substances.
Storing ammunition
If you have an explosives licence, ammunition (small arms cartridges) must be stored in the magazine specified in your licence.
If you do not have an explosives licence, ammunition must be stored in a dwelling (such as a house, apartment or cottage) or a storage unit.
Storage requirements for users
You are permitted to store up to 225 kilograms of ammunition (the mass of the explosive excluding the packaging, container, shell casing or projectile) in a dwelling (such as a house, apartment or cottage) or a storage unit without a licence. To store more than 225 kilograms of ammunition (the mass of the explosive, excluding the packaging, container, shell casing or projectile), you must have an explosives licence.
Dwelling
You must store the ammunition away from flammable substances and sources of ignition. You must ensure that it can be accessed only by people you have authorized.
Storage unit
You are permitted to store the ammunition in a storage unit if:
The storage unit must be in a dry place, away from flammable substances and sources of ignition.
The storage unit must be constructed and maintained to prevent unauthorized access and protect the contents from weather.
The storage unit is a container, it must not block exit in case of fire.
The storage unit is not a container, all exits must be kept clear.
The shelving in the storage unit is made from a non-sparking material (for example, wood or painted metal).
Only propellant powder, primers (percussion caps) and/or black powder cartouches are stored with the ammunition.
Ammunition, propellant powder, primers and black powder cartouches are stored separately (for example, on different shelves or separated by a wooden barrier).
The storage unit is monitored when it is unlocked.
The storage unit is kept clean, dry, organized and free of grit.
Any spill, leakage or other contamination is cleaned up immediately.
You take steps to minimize the risk of fire in or near the storage unit.
You post a sign that displays the words “Danger — Fire Hazard/Risque d’incendie” in letters at least 10 centimetres high on the storage unit in a clearly visible location. The sign must also prohibit smoking using letters or a symbol at least 10 centimetres high.