Word/short phrase for "timespan has not yet started"

You can say that the license is unbegun.

(Collins Dictionary)

Unbegun - not commenced; not yet started

You could use pending

http://www.thefreedictionary.com/pending

pending  
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Related to pending: sale pending
pend·ing  (pĕn′dĭng)
adj.
1. Not yet decided or settled; awaiting conclusion or confirmation.
2. Impending; imminent.
prep.
1. While in the process of; during.
2. While awaiting; until.

or, upcoming

http://www.thefreedictionary.com/upcoming

up·com·ing  (ŭp′kŭm′ĭng)
adj.
Occurring soon; forthcoming.

upcoming (ˌʌpˈkʌmɪŋ)
adj
coming soon; forthcoming

up•com•ing (ˈʌpˌkʌm ɪŋ) 
adj.
coming up; about to take place, appear, or be presented: the upcoming spring fashions.

Try prospective as in "prospective license," "valid license" and "expired license."

Merriam Webster

effective in the future.