Thesaurus:lasting

• abiding

• chronic

• continuate (obsolete)

• diuturnal

• durative

• enduring

• extending

• lasting

• long-drawn-out

• long-lasting

• longevous (rare)

• longsome (archaic or dialect)

• perdurable

• prolonged

• protracted

• dureless (obsolete)

• ephemeral    [WS]

• eternal    [WS]

• unlasting

Indefinite period:

• durable

• permanent

• intransient

• ultrapermanent

Non-specific period; specific reference:

• hourslong

• minuteslong

•   —

• all-day

• all-night

• dayslong

• nightlong

• nychthemeral

•   —

• weeklong

• weekslong

•   —

• monthslong

• seasonlong

• springlong

•   —

• decadeslong

• perennial

• plurennial

• pluriennial

• subdecadal

• yearslong

Non-specific period; non-specific reference:

• careerlong

• lifelong

• livelong

Specific period:

• diary (obsolete)

• triduan

• trinoctial

• quatridual

• hebdomadal (obsolete)

• menstrual

• annual

• biennial

• triennial

• quadrennial

• quinquennial

• sextennial

• septennial

• octennial

• novennial

• decennary

• decennal

• decennial

• decennalian

• quindecennial

• vicennial

• centennial

Not subject to decay:

• imperishable

• undecaying

• unfading

• unpaling

• unwasting

Not deteriorating:

• indestructible

• indissoluble

• undestroyable

• unbreakable

• unruinable

• unwreckable

Having a long lifespan:

• long-lived

• longeval (rare)

• longevous (rare)