Activations purchase

[Pcub]

I bought a sliver activation for my account too early. How long do the activations last without using them? I have about 18 more days before I really have to renew and want to know if the activation I bought today will still be good to use on April 3rd?

[Bowser]

I do not think buying a new subscription wile already has one pauses the one thats recently bought, however i might be wrong.

[Pcub]

Do the activations maybe stack so If I use it now, will I get 3 months plus 18 days that's still remaining on my old activation?