What is it called when you do something once and benefit from it for a long time or forever
Solution 1:
In specific regards to performance art, residuals are payments made in perpetuity for subsequent broadcasts or showings of your work.
A residual is a payment made to the creator of performance art for subsequent showings or screenings of the work. A typical use is in the payment of residuals for television reruns. The word is often used in the plural form. - Wikipedia
Solution 2:
You're reaping the rewards.
reap: to gain or get (something) as a reward for or result of some action or enterprise Collins English Dictionary
Alternately, you could say that you're cashing in (on some action or enterprise).
cash in: to obtain a profit or other advantage by timely exploitation AHD
cash in on: to take advantage of or capitalize on WordNet by Farlex
Solution 3:
You could consider using "(long-term) portfolio" which means:
(business) A collection of assets generally.
[Wiktionary]
A range of investments held by a person or organization:
[Oxford Online Dictionary]
Portfolio is not necessarily limited to "stocks/securities" or "bonds" and it can include various things you have for your investment and future returns.
Solution 4:
I suppose you might be talking about the phrase 'in perpetuity':
- a. in (also for, †to) perpetuity: for all time, for ever; for an unlimited or indefinitely long period.
["perpetuity, n.". OED Online. September 2015. Oxford University Press. http://www.oed.com/view/Entry/141355?redirectedFrom=in+perpetuity (accessed November 14, 2015).]
In the context of your examples:
- Publishing a book or cutting an album may earn the creator royalties in perpetuity.
- Some work, done once, may earn profits in perpetuity.
- If you buy something that will last a lifetime, you will benefit in perpetuity.
- You may spend more money now, but will save money in perpetuity.