Renew cheat subscription

Don't suppose anyone could answer a quick question.
I have about a week left of my CSGO subscription, what happens if I purchase a life time CSGO lifetime subscription or a Master Package lifetime subscription BEFORE my CSGO one ends? Does it add it on? How can you add 7 days to lifetime??
Pls help :)

lifetime never expires so it will overwrite your current subscription, but, if you purchase 1 year one and you have 7 days left you gonna have 367 days

ty