It has been a long, drawn-out, and expensive legal battle, lasting nearly five years. Is an end finally in sight? Samsung has agreed to pay Apple (NASDAQ:AAPL) $548 million in a settlement for infringing on Apple's patents (via FOSS Patents). Here's what investors need to know.

iPhone 6. The disputed patents are primarily related to smartphone technology. Image source: Apple.

The financial impact
For Apple, $548 million in additional cash is nearly irrelevant to the company's finances. The company's net income was $11.1 billion in its most recent quarter alone. And during the trailing 12 months Apple's net income was $53.4 billion.

But for Samsung, $548 million is more noticeable. The settlement amount represents 3% of the company's annual net income during the trailing 12 months. Magnifying the negative impact the financial hit, Samsung's business is on the decline, with annual net income falling about 30% over the last two years.

But even if Samsung pays $548 million to Apple, there's still a chance the cash could come back to the South Korean company, according an excerpt from Samsung's case management statement cited by FOSS Patents.

Samsung continues to reserve all rights to obtain reimbursement from Apple and/or payment by Apple of all amounts required to be paid as taxes. [...] Samsung further reserves all rights to reclaim or obtain reimbursement of any judgment amounts paid by Samsung to any entity in the event the partial judgment is reversed, modified, vacated or set aside on appeal or otherwise, including as a result of any proceedings before the USPTO addressing the patents at issue or as a result of any petition for writ of certiorari filed with the Supreme Court.

When will the battle end?
FOSS Patents advises those following the ongoing battle that this settlement agreement isn't a sign of a definitive end to the costly patent war.

Also noted in Samsung's case management statement is a clear declaration that "the Patent Trial and Appeal Board has issued a final decision of invalidity on the '915 Patent, and Apple filed a notice of appeal to the Federal Circuit in the USPTO last week."

And FOSS Patents notes that there's more uncertainty for Apple beyond the '915 patent.

The situation surrounding the '915 patent is not the only factor of uncertainty here for Apple. Samsung announced in the summer that it would file a petition for writ of certiorari (request for Supreme Court review) concerning design patent damages. If the top U.S. court agreed to hear that matter and agreed with what will likely be a broad industry coalition, there would have to be a retrial.

Apple has been criticized for pursuing "fool's gold patents," or patenting more than is necessary. Critics argue these actions stifle innovation. But Apple believes some of its simplest iPhone patents were among the most revolutionary in pioneering the smartphone we know today.

What should investors expect to happen next? If the past is any indication of the future, Samsung will continue to appeal Apple's claims against Samsung.